Vectors are quantities that have both a magnitude (numerical value) and a direction. Examples of quantities that are vectors include displacement, velocity, momentum, and force.

Scalars are quantities that have a magnitude but no direction. Examples of scalars include time, mass, energy, speed, distance.

Physics: Practice Questions Flashcards by Jeff Piechocki

Kinematics & Motion

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Unit Question:

Definition of a Meter

Since 1983 the standard meter has been defined in terms of the distance light travels in 1/(3 x 10^8) seconds.

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Examples of Vectors

Vectors are quantities that have both a magnitude (numerical value) and a direction.
Examples of quantities that are vectors include displacement, velocity, momentum, and force.

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Provide the name of the scalar quantity associated with each of the following vector’s magnitude:
* Displacement
* Velocity

Answer: Distance is the scalar quantity of displacement’s magnitude; speed is the scalar quantity to velocity’s magnitude.

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Give the term that describes the speed and direction of an object.

Answer: Velocity

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Solve:

If the displacement, x, of an object is related to its velocity, v, by the equation x = Av, determine the physical quantity represented by A.

Answer: t for “time” (displacement = velocity * time)

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Examples of Scalars

Scalars are quantities that have a magnitude but no direction.
Examples of scalars include time, mass, energy, speed, distance.

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Solve:

Which one of the following four outcomes is true when a 6.5-gram feather and 2.5-kilogram ball are in free-fall motion assuming no air resistance after being released from the same height at the same time?

The ball will strike the ground before the feather.
The feather will strike the ground before the ball.
The feather and the ball will strike the ground at the same time.
There is not enough information to determine the outcome.

Answer: 3. The feather and the ball will strike the ground at the same time.

(Any object dropped from the same height, regardless of mass, will strike the ground at the same time in the absence of air resistance.)

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Solve:

The average distance from the sun to Jupiter is approximately 779 million kilometers.

To the nearest minute, calculate the time it takes for sunlight to reach Jupiter.

Answer: 43 minutes

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Solve:

A group of students is traveling 100. miles to Walt Disney World to participate in the academic challenge. The group completes the first half of the trip with a speed of 65.O miles per hour and the second half with a speed of 75.0 miles per hour.

To three significant digits, determine in miles per hour the average speed of the trip.

Answer: 69.6 (miles per hour)

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Solve:

To three significant digits, calculate in meters per second Usain Bolt’s average speed when he set the world record in 2009 by winning the 100-meter dash in a time of 9.58 seconds.

Answer: 10.4 meters per second

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Solve:

To three significant digits, calculate in meters per second Florence Griffith-Joyner’s average speed when she set the world record in 1988 winning the 100-meter dash in a time of 10.49 seconds.

Answer: 9.53 meters per second

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Solve:

To three significant digits, determine in meters per second the increase in speed of a roller coaster at the bottom of a 75.0 meter drop, neglecting the effects of air resistance.

Answer: 38.3 (meters per second)

(For this one, I also got 38.36, which should be rounded to 38.34)

I would have challenged that if it were counted wrong.

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Solve:

Marcia flew her ultralight plane to a nearby town against a head wind of 15 kilometers per hour in 2 hours and 20 minutes. The return trip under the same wind conditions took 1 hour and 24 minutes.

Find the plane’s air speed in km/h.

Answer: 60 km/hr

(This was a team question.)

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Solve:

On Memorial Day weekend I drove the 112 miles from Cincinnati to Indianapolis in one hour and forty-two minutes. My average speed was [BLANK] to the nearest whole mile-per-hour which was considerably less than the cars participating in the Indy 500 at the Brick Yard.

(This was a team question.)

Answer: 66 mph

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Solve:

To two significant digits, calculate in meters per second the speed of a free-falling object after 6.0 seconds assuming the object starts from rest.

Answer: 59 (meters per second)
final speed = acceleration * time
vf = (9.81) * (6.0)

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Solve:

Claudius has designed a waterfall as part of an aqueduct. The waterfall is 10 meters tall. Determine in meters per second, the speed of the water at the bottom of the waterfall.

Answer: 14 meters per second

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Solve:

I wonder to two significant digits what Alice’s landing speed would be in meters per second, if she fell down a rabbit hole that was 15 meters in depth. Assume she started from rest and there is no air resistance in the rabbit hole.

Answer: 17 meters per second

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Solve:

To one significant digit, calculate in meters per second the speed of a set of keys, just as they strike the ground, given that they are thrown downward with an initial speed of 3 meters per second from the top of a 20 meter parking garage.

Answer: 20 meters per second

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Solve:

Bill is standing at the top of a 50. meter tall building and throws a set of keys down to Ted with an initial speed of 1.5 meters per second. To two significant digits, determine in meters per second, the speed of the keys when they impact the ground.

Answer: 31 meters per second

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Solve:

To three significant digits, determine in meters the displacement of a ball that is launched upward with an initial velocity of 25.0 meters per second after the ball has been in flight for 3.75 seconds.

Answer: 24.8 meters

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Solve:

To two significant digits calculate in meters per second squared the acceleration of a car traveling due east that is uniformly decreasing its speed from 25 meters per second to 15 meters per second over a 9.5 second period of time.

Answer: -1.1 meters per second squared (or 1.1 m/s^2 WEST.)
Acceleration is the change in velocity over the change in time. Here, it’s -10 / 9.5. The direction is negative because the car is decelerating (or accelerating in the opposite direction.)

(If a direction is not included, you’ll be prompted for more information)

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To two significant digits calculate in meters per second squared the average acceleration of an object traveling in a straight line given that the object start from rest at t equals zero and is traveling at a speed of 12 meters per second at t equals 6.5 seconds.

Answer: 1.8 meters per second squared
Acceleration is change in velocity over the change in time. The change in velocity is 12 m/s, the change in time is 6.5 seconds, therefore the answer is 12 / 6.5 = 1.8 meters per second squared.

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Solve:

Aladdin is traveling on his “limo-sized” magic carpet at a constant speed of 15 m/s and is walking at a
speed of 1.0 m/s from the front of the carpet to the back of the carpet. At what speed in m/s is Aladdin
traveling relative to a stationary observer on the street?

Answer: 14 m/s
This is a vector addition problem. The carpet is traveling 15 m/s in the positive direction, Aladdin is traveling 1.0 m/s in the negative direction, therefore an observer sees the sum: 15 + (-1) = 14 m/s.

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# Solve: To two significant digits, calculate in meters the distance a dropped object has fallen in 5.5 seconds. Neglect air resistance.

* **Answer:** 150 meters

# Solve: To two significant digits, determine in meters per second the final speed of an object thrown from a height of 75 meters given that the object's initial velocity is - 7.5 meters per second.

* **Answer:** 39 meters per second

# Solve: To three significant digits, determine in meters the maximum height of a rocket launched from rest with an acceleration of 58.8 meters per second squared given that the acceleration lasts for 12.5 seconds and the rocket continues to coast.

* **Answer:** 32,200 meters ## Footnote (GPT gets 32,100 meters.)

# Solve: To two significant digits, calculate in meters the minimum length of the runway necessary for an airplane needing to reach a speed of 75 meters per second for takeoff given the engines can exert a uniform acceleration of 2.5 meters per second squared.

* **Answer:** 1100 meters

# Solve: To two significant digits, determine the speed in meters per second of a 15.0 kg ball thrown straight down from a height of 2.5 meters, which strikes the floor with a speed of 9.0 meters per second. | (The question is asking for the inital velocity of the thrown ball.)

* **Answer:** 5.7 meters per second

# Solve: To two significant figures, calculate in meters, the maximum height reached by a 3.5 kg ball thrown upward at an initial velocity of 11.5 meters per second assuming no air resistance.

* **Answer:** 6.7 meters * You can use conservation of energy here (set KE = PE, solve for h) or you can use the max height formula (Max height = (initial v squared) / (2 * grav)). | (Remember: Mass has no impact on kinematics if no air resistance)

# Solve: Arthur Dent threw himself toward the ground from a height of 16,700 meters. To two significant figures, determine in seconds the time it would have taken him to hit the ground had he not missed. Neglect initial velocity; acceleration of gravity is 18.93 meters per second squared. ## Footnote (I don't know anything about Hitchhiker's Guide to the Galaxy or why we're using a weird number for acceleration due to gravity.)

* **Answer:** 42 seconds ## Footnote (Oh, I get it. 42 is the answer to everything. Or something. I haven't read the book.)

# Solve: Thor throws his hammer vertically straight up with an initial velocity of 100. meters per second. To two significant digits, determine in meters the maximum height reached by Thor’s hammer.

* **Answer:** 510 meters * Seems like a great occasion to use the max height formula (max height = (initial velocity squared) / (2 * g ))

# Solve: To two significant digits, calculate in meters per second the speed at which Mario will hit the ground given that he falls from a platform 10. meters high and misses the steel girder parallel to the platform. ## Footnote (Team Question)

* **Answer:** 14 meters per second

# Solve: To two significant digits calculate the magnitude of the average acceleration in meters per second squared of a car that is traveling at a speed of 15 meters per second and then increases its speed to 35 meters per second in 22 seconds.

* **Answer:** 0.91 m/s^2 * Average acceleration is the change in velocity over the change in time. Here, that means (20 m/s) / (22 s). ## Footnote (Note: Answer key says "do not accept a negative answer")

# Solve: A projectile is shot straight up into the air with an initial speed of 25 meters per second. To two significant digits determine in seconds the time it takes the projectile to reach its maximum height.

* **Answer:** 2.6 seconds | (The answer key says 32 seconds. There's no way.)

# Solve: To two significant digits, calculate in meters the range of a projectile fired horizontally at a speed of 55 meters per second from a 120-meter-tall hill.

* **Answer:** 270 meters per second

Isaac drops an apple from the top of a 65-meter-tall tower. To two significant digits, determine in meters per second the speed of the apple when it reaches the ground given that the apple starts from rest.

* **Answer:** 36 meters per second

# Solve: For the next question you will need this information. A train is traveling North at a constant speed of 2.0 meters per second when it begins to accelerate at a rate of 0.80 meters per second squared. At the same time the train begins to accelerate, a ticket collector drops a coin which takes one-half of a second to hit the floor. Neglect friction. Complete the following statement using one of the four given choices. Relative to a spot on the floor directly beneath the point where the coin was released, the coin will land ... Choice 1: 1.6 meters toward the rear of the train. Choice 2: directly on the spot. Choice 3: 0.10 meters toward the rear of the train. Choice 4: 0 .90 meters toward the rear of the train.

* **Answer:** Choice 3, 0.10 meters toward the rear of the train. * The question is essentially asking how far the train moved if it accelerated forward at 0.80 meters per second squared for half a second.

To two significant digits, calculate in meters the minimum length of the runway necessary for an airplane needing to reach a speed of 75 meters per second for takeoff given the engines can exert a uniform acceleration of 2.5 meters per second squared.

# Solve: To two significant digits, calculate in meters per second, the final velocity of a vehicle that uniformly accelerates from rest at 1.8 meters per second squared over a displacement of 75 m.

* **Answer:** 16 meters per second

# Solve: You cross a stream from west to east at a point where it is 10 meters wide and is flowing south at a rate of 3 meters per second. Your boat can travel 4 meters per second in still water. This is a three-part question. Determine the following needed for the trip: 1. the speed in meters per second as seen by an observer on the shore 2. the resulting angle to the neatest degree of travel measured clockwise from due North 3. the time in seconds ## Footnote (This is a weird one from 1996.)

* **Part 1 Answer:** 5 meters per second * **Part 2 Answer:** 127 degrees * **Part 3 Answer:** 2.5 seconds

# Solve: To two significant digits calculate in meters per second the speed of an object on a planet where the acceleration due to gravity is 15 meters per second squared after the object has been in freefall for 3.0 seconds.

* **Answer:** 45 m/s * This one is straightforward. If the speed increases by 15 m/s per second for three seconds, the final speed is 45 m/s.

# Solve: To three significant digits, determine the speed in meters per second of Dilbert’s computer as it impacts his boss’s car when dropped from a height of 30.0 meters.

* **Answer:** 24.2

# Solve: A cat on top of a refrigerator rolls off and lands on the floor with a speed of 6.2 meters per second. To the nearest tenth, calculate in meters, the height of the refrigerator.

* **Answer:** 2.0 meters

# Solve: A cannon ball is projected towards a cliff with an initial speed of 42 meters per second at an angle of 60. degrees above the horizontal. To two significant digits, calculate in meters the height of the cliff given that the cannon ball lands on the top of the cliff 5.5 seconds after being fired

* **Answer:** 52 meters

# Solve: To two significant digits, calculate in seconds the amount of time it would take a projectile to impact the ground given that it is thrown downward with an initial velocity of 10. meters per second from a height of 50. meters.

* **Answer:** 2.3 seconds

# Solve: To three significant digits, determine in seconds the time it takes for an object thrown down from a height of 75.0 meters at an initial velocity of 15.0 meters per second to hit the ground. Neglect air resistance.

* **Answer:** 2.67 seconds | (This is a weird one requiring the quadratic equation.)

# Solve:

# Solve: A 5.0-kilogram ball is dropped from a height of 45 meters. To two significant digits calculate in meters per second the speed of the ball as it just strikes the ground.

* **Answer:** 30 meters per second

# Solve: Galileo dropped a wooden sphere from the Leaning Tower of Pisa at a height of 55 meters. To two significant digits, calculate in seconds the time it took the sphere to reach the ground. Ignore air resistance.

* **Answer:** 3.4 seconds

# Solve: The CN Tower in Toronto stands at a height of 553 meters. The Burj Dubai skyscraper will reach a height of 800. meters. If a penny is dropped from the top of each structure, to two significant digits, calculate in meters per second the difference in the speed of the pennies just as they hit the ground after falling.

* **Answer:** 21 meters per second

# Solve: A 1.3-kilogram watermelon is dropped from a 25-meter high cliff at the same time a person at the bottom of the cliff shoots an arrow straight towards the watermelon from a height of 2.0 meters above the ground. The arrow strikes the watermelon 0.35 seconds later. To two significant digits calculate in meters the height above the ground at which the arrow strikes the watermelon.

* **Answer:** 24 meters

# Solve: To two significant digits calculate in meters the height of the center of a target 59 meters from an archer who accurately shoots an arrow at an angle of 35 degrees at an initial velocity of 25 meters per second from a height of 1.5 meters.

* **Answer:** 2.1 meters

# Solve: Tom Brady throws a football horizontally with an initial speed of 25 meters per second from a height of 10. meters. To two significant figures, calculate in meters the distance the ball traveled in the air. Neglect air resistance.

* **Answer:** 36 meters | (They should have specifically asked for the *horizontal* distance.)

# Solve: To two significant digits, determine in meters the distance an object falls under the influence of gravity given that the initial velocity of the body is 5. 0 meters per second and the final velocity is 90. meters per second. Assume no air resistance.

* **Answer:** 410 meters

# Solve: To one significant digit, determine in meters the distance from a 70 meter tall vertical cliff a rock would land given that the rock is thrown horizontally at an initial speed of 15 meters per second.

* **Answer:** 60 meters

# Solve: To one significant digit, determine in kilometers the distance from the separation point that an autonomous drone ship must be placed in order to recover a Falcon 9 first stage, given that the stage separates at an altitude of 80 kilometers with a speed of 2100 meters per second at an angle of 53 degrees above the horizontal. Assume the drone ship is located on the surface of the Earth and neglect air resistance. ## Footnote (They should have clarified this: The "Falcon 9 First Stage" is part of a reusable SpaceX rocket that falls back to Earth and is recovered by a self-piloting 'drone ship' boat on Earth.)

* **Answer:** 500 meters

# Solve: To two significant digits, calculate in meters per second squared the acceleration of a car that starts from rest and travels a distance of 150 meters over a time interval of 4.7 seconds.

* **Answer:** 14 meters per second squared

# Solve: Given that sound in air is traveling one kilometer every three seconds, to three significant digits calculate in meters the distance of a storm when the difference between a flash of lightning and a clap of thunder is 2 seconds.

* **Answer:** 667 meters

# Solve: To two significant digits, calculate in meters per second the initial speed of a wolverine that leaps a horizontal distance of 73 meters at an angle of 45°. Neglect air resistance.

* **Answer:** 27 meters per second

# Solve: A cyclist passes a checkpoint at a speed of 4.7 meters per second. As he passes the checkpoint, he begins to slow down at a rate of 0.25 meters per second squared. To two significant digits state the distance in meters the cyclist will have traveled upon coming to rest.

* **Answer:** 44 meters

# Solve: To two significant digits calculate in meters the distance required for a roller coaster car to come to rest when it is initially traveling at 12.5 meters per second and begins to uniformly accelerate at a rate of -6.5 meters per second squared.

* **Answer**: 12 meters

# Solve: To three significant digits, determine in meters per second squared the acceleration of a car starting from rest that accelerates to 25.0 meters per second over a distance of 75.0 meters.

* **Answer:** 4.17 meters per seconds squared

To three significant digits, determine the distance in meters between two grocery store bag boys who are rolling a certain pickle jar starting from rest with an acceleration of .500 meters per second squared down a grocery aisle given that it takes 5.00 seconds for the jar to travel from one bag boy to the other.

* **Answer:** 6.25 meters

# Solve: At a recent regatta in California, The San Diego Crew Classic, results from the Men’s Cal-Visitor’s Cup Grand Final with their times were as follows: * Oregon State University 6:17.12 * U.C. San Diego 6:24.55 * Columbia University 6:25.71 * U.C. Irvine 6:27.37 * Wichita State University 6:30.34 * U.C. Santa Barbara 6:31.56 To two significant digits calculate in meters the distance U.C. Irvine finished behind Oregon State University if the course was 2000. meters long. Assume constant velocity for all boats. ## Footnote (This was a handout question.)

* **Answer:** 53 meters ## Footnote (Note: GPT arrived at 54 meters for its answer.)

Forces

Identify the quantity that a **spring scale** measures and its units.

**Answer:** A spring scale measures **force** in **Newtons.**

Which one or ones of the following four have the unit of force? 1. friction 2. coefficient of friction 3. weight 4. mass

**Answers:** 1 and 3 (friction and weight)

In physics, what is represented by the lowercase Greek letter, mu?

**Answer:** Coefficient of Friction

# 0. Which one of the following four could not produce equilibrium with a 4 Newton force and a 12 Newton force acting concurrently on a point? 1. 6 Newtons 2. 16 Newtons 3. 10 Newtons 4. 8 Newtons

**Answer:** 1. 6 Newtons

A 1000-kilogram automobile accelerates from rest to 20 meters per second in 5 seconds. Calculate the force in newtons which the road exerts on the car in order to cause this acceleration.

**Answer:** 4000 Newtons

To two significant digits, determine in meters per second squared the acceleration of a Cessna 172 given that the engine’s propeller produces a thrust of 1,700 Newtons, drag is 1,200 Newtons, and the aircraft has a mass of 1,043 kilograms.

**Answer:** 0.48 meters per seconds squared

Donald and Goofy are arguing over a CAC lanyard that has a mass of 2.5 kilograms attached to it. Donald pulls to the left on the lanyard with a horizontal force of 25 Newtons, and Goofy pulls on it to the right with a horizontal force of 28 Newtons. To two significant digits, calculate in meters per second squared the magnitude of acceleration of the mass.

**Answer:** 1.2 (meters per second squared)

To two significant digits, determine in newtons the force that causes a 1,200 kilogram automobile to accelerate from 5.0 meters per second to 15 meters per second in 7.0 seconds.

**Answer:** 1700 Newtons

To two significant digits, calculate the acceleration in meters per second squared of a 25 kilogram crate, initially at rest, given that a 1,200 newton force is applied. Assume no friction.

**Answer:** 48 meters per second squared

To two significant digits calculate in newtons the magnitude of the normal force acting. on a 102-kilogram block resting on a 32-degree inclined plane.

**Answer:** 850 Newtons

The coefficient of friction between a 10.0-kilogram block and an inclined plane is 0.700 If the angle of the plane is increased slowly, then calculate to two significant digits the degree measure of the angle at which the box will just begin to slide.

**Answer:** 35 degrees

To three significant digits, determine in meters per second squared the acceleration of a 10.0 kilogram mass up a plane inclined at an angle of 37.0 degrees given that mass 1 is pulled via an ideal string over an ideal pulley that is connected to a 15.0 Kg mass hanging vertically from the pulley. Assume the coefficient of friction is 0.350.

**Answer:** 2.43 meters per second squared

To three significant digits, determine the coefficient of static friction for a block that rests on an inclined plane given that the plane is at an angle of 53.0°.

**Answer:** 1.33

To two significant digits, determine in meters per second squared the acceleration of a 15 kilogram box moved by a 120 Newton force across a surface whose coefficient of friction is 0.65.

**Answer:** 1.6 meters per second squared

To two significant digits, determine the minimum coefficient of static friction between a 25 kilogram box and the surface of a ramp with an angle of inclination of 37°.

**Answer:** 0.75

To three significant digits, calculate the coefficient of static friction of an object just before it begins to slide down a ramp inclined at 37.0 degrees.

**Answer**: 0.754

To three significant digits, determine in meters per second squared the acceleration of a 2.50 kilogram wood block down a ramp that is inclined at 37.0° with respect to the horizontal and coefficient of friction of 0.155.

**Answer:** 4.68 meters per second squared

To two significant digits, calculate in meters per second squared the acceleration of a 25- kilogram box that is sliding down a ramp that is inclined at 53 degrees with respect to the horizontal. The coefficient of friction is 0.37.

**Answer:** 5.6 meters per second squared

To two significant digits, determine in meters per second squared the acceleration of a 30 kilogram block down a ramp having a coefficient of kinetic friction of 0.20 and making an angle of 25 degrees with respect to the horizontal.

**Answer:** 2.4 meters per second squared

To one significant digit, determine in meters per second squared the magnitude of acceleration for a skier skiing down a 30 degree slope with respect to the horizontal. Assume the slope is frictionless.

**Answer:** 5 meters per second squared

To three significant digits, determine the coefficient of kinetic friction for a 45.0 kilogram box on a level surface when a 200. Newton constant force is applied.

**Answer:** 0.454

To two significant digits calculate the coefficient of static friction between a 2.6-kilogram block and an incline if the maximum angle of the incline just before the block slips is 28 degrees with the horizontal.

**Answer:** 0.53

What is the largest possible resultant force, in newtons, of two concurrent forces with magnitudes of 2 newtons and 5 newtons?

**Answer:** 7 Newtons

Give the magnitude of two concurrent forces that have a maximum resultant of 235 newtons and a minimum resultant of 5.00 newtons.

**Answer:** 120 and 115 Newtons

To two significant digits, determine in Newtons the weight of a 15 kilogram object.

**Answer:** 150 Newtons

If Tara has a mass of 50 kilograms, to one significant digit, determine her weight in Newtons

**Answer:** 500 Newtons

The combined mass of the twin solid rocket boosters on the Artemis 1 rocket is 3.2 million kilograms. To two significant figures, calculate in Newtons the weight of the boosters.

**Answer:** 31,000,000 (or 3.1 x 10^7) Newtons

To two significant digits, determine in kilograms the mass of an object if an applied force of 25 Newtons produces an acceleration of 1.2 meters per second squared.

**Answer:** 21 kilograms

A Ford Mustang has a mass of 1800 kilograms. Given that the Mustang requires an applied force of 3100 newtons to accelerate, to two significant digits, determine in meters per second squared the magnitude of the acceleration.

**Answer:** 1.7 meters per second squared

To two significant digits, determine in kilograms the mass of a truck given that an applied force of 2500 Newtons is required to accelerate the truck at 0.65 meters per second squared.

**Answer:** 3800 kilograms

Bill and Ted are each pulling on a 3-kilogram box of nachos. Bill pulls to the left with a force of 60 newtons and Ted pulls to the right with a force of 75 newtons. To one significant digit, determine in meters per second squared the magnitude of the acceleration of the box of nachos.

**Answer:** 5 meters per second squared

A 12-kilogram box is pulled across the floor with a horizontal force of 55 newtons. Given that the frictional force is 14 newtons, to two significant figures, calculate in meters per second squared the magnitude of the acceleration of the box.

**Answer:** 3.5 meters per second squared

A 25-kilogram box is pulled across the floor with a horizontal force of 65 newtons. Given that the frictional force is 12 newtons, to two significant figures, calculate in meters per second squared the magnitude of the acceleration of the box.

**Answer:** 2.1 meters per second squared

Gene and Howard are each pulling on a 1.5-kilogram rope during a tug-of-war competition. Gene pulls to the left with a force of 67 newtons and Howard pulls to the right with a force 66 newtons. To two significant figures, calculate in meters per second squared the magnitude of the acceleration of the rope.

**Answer:** 0.67 meters per second squared

To three significant digits calculate in newtons the apparent weight of a woman with a mass of 45.0 kg standing on a scale in an ascending elevator accelerating at the rate of 2.50 meters per second.

**Answer:** 554 (Newtons)

To two significant digits, determine in Newtons the weight as indicated by a scale for a 55 kilogram person who is descending in one of the Contemporary's elevators, given that the elevator is descending at 0.15 meters per second squared.

**Answer:** 530 Newtons

To two significant digits calculate respectively in newtons the vertical and horizontal components of a 75-newton force acting at an angle of 45 degrees.

**Answer**: 53 and 53 Newtons

A 739 kilogtam smart car travels with an initial velocity of 15 meters per second. The car takes 5.0 seconds to come to rest. To two significant digits, determine in Newtons the magnitude of the braking force.

**Answer:** 2,200 Newtons

To two significant digits, determine in Newtons the tension in the string of an ideal Atwood machine given that mass 1 is 15 kilograms and mass 2 is 12 kilograms. Assume the string is massless and extensionless, and the pulley is frictionless.

**Answer** 130 Newtons

To two significant digits, determine in meters per second squared the magnitude of the acceleration produced by two masses on an ideal Atwood machine given that mass 1 is 15 kilograms and mass 2 is 18 kilograms. Assume the string is massless and extensionless, and the pulley is frictionless.

**Answer:** 0.89 meters per second squared

To two significant digits, calculate in meters per second squared the magnitude of the acceleration of a 1.01-kilogram mass attached to a 0.99-kilogram mass by a massless string on an Atwood machine. Neglect friction and assume the pulley is massless.

**Answer:** 0.098 meters per second squared

The engine of a certain boat exerts a 415-newton force in the northward direction while the wind is pushing on the boat with a force of 325 newtons in the westerly direction. The current exerts a force of 250 newtons in the southerly direction. To two significant digits calculate respectively in newtons and degrees the magnitude and direction of the resultant force relative to the positive x-axis acting on the boat.

**Answer:** 360 and 150 Newtons

To three significant digits, determine in meters per second squared the magnitude of acceleration of an object that has a mass of 25.0 kg if a force of 100. Newtons is required to move it.

**Answer:** 4.00 meters per second squared

Which one or ones of the following four statements are correct concerning Newton's First Law? 1. explains the resistance to any change in motion 2. explains, in part, centrifugal force 3. also known as the law of inertia 4. plays a role in the conservation of angular momentum

**Answer:** All four are correct.

Which one of the following four is a measure of the inertia of a moving object? 1. mass 2. momentum 3. power 4. energy

**Answer:** 1. Mass

This refers to an upward force caused by displacement of a fluid

Buoyant Force

# Solve: A boat displaces 6.7 x 10^8 Newtons of fresh water when floating. To two significant digits, calculate in cubic meters the difference in volume of water displaced if the boat is now placed in salt water, where the density of salt water is 1020 kilograms per meter cubed. The density of freshwater is 998 kilograms per meter cubed.

* **Answer:** 1500 cubic meters

# Solve: To two significant digits, determine the coefficient of sliding friction between the blades of an 81 Newton sled that is pulled across a driveway at constant speed with a 38 Newton force exerted on the handle causing an angle of 42 degrees with the ground.

* **Answer:** 0.51

To two significant digits calculate the coefficient of friction for a 20-kilogram mass being pulled along a level surface at a constant velocity of 3 .2 meters per second by a horizontal force of 130 newtons.

**Answer:** 0.66

A 15 kg block is being pulled with a 18 Newton force across a horizontal surface at constant velocity. To two significant digits, calculate the coefficient of sliding friction between the block and the ground.

**Answer:** 0.12

To two significant digits calculate the coefficient of friction between a 75-kilogram box and the floor if the box is being pulled across the floor with a constant 120-newton force at an angle of35 degrees to the horizontal.

**Answer:** 0.15

To two significant digits calculate in meters per second squared the constant acceleration of the block if the coefficient of kinetic friction between the block and the horizontal surface is 0.15.

**Answer:** 1.5 meters per second

To two significant digits, determine in meters per second squared the acceleration of a 15 kilogram box moved by a 120 Newton force across a surface whose coefficient of friction is 0.65.

**Answer:** 1.6 meters per second squared

# Solve: To two significant digits, calculate the coefficient of friction between a horizontal surface and a 25 kilogram box sliding at a constant speed due to an applied horizontal force of 75 Newtons.

* **Answer:** 0.31

# Solve: A small child pulls a 25 kilogram toboggan across a flat surface with a horizontal force of 75 Newtons at a constant speed. To one significant digit, determine the coefficient of kinetic friction between the toboggan and the flat surface.

* **Answer:** 0.3

# Solve: To two significant digits determine the coefficient of kinetic friction of a 25 kg object on a horizontal surface given that the object is dragged across the surface at a constant speed by a 75-newton force.

* **Answer:** 0.31

A Tesla Roadster has a mass of 1300 kilograms and a magnitude of acceleration of 13.8 meters per second squared. To two significant digits, calculate in Newtons the force applied to the Tesla.

* **Answer:** 18,000 Newtons

A Tesla Model X has a mass of 2300 kilograms and a magnitude of acceleration of 24.6 meters per second squared. To two significant digits, calculate in Newtons the force applied to the Tesla.

**Answer:** 57,000 Newtons

Circular Motion

# Provide the formula for: Calculating the **centripetal force** | (for an object moving in a circle.)

Centripetal Force = [(mass) * (velocity squared)] / (radius) ## Footnote Fc is in Newtons, m in kilograms, v in meters/sec, r in meters

Calculating **centripetal acceleration**

# Memorize this: Give the value for **G, the gravitational constant** to three significant figures.

Calculating minimum **velocity required for orbit** | (This is called the **critical speed.**)

For an object in uniform circular motion, the centripetal **force** is in this direction.

Towards the center of the circle

For an object in uniform circular motion, the centripetal **acceleration** is always in this direction.

Towards the center of the circle

Which denotes the quantity represented by the area under a velocity vs. time graph?

Displacement | (Also, the slope of a v vs. t graph is **acceleration**.)

The slope of a line on a displacement-time graph represents [BLANK].

* **Answer:** (Average) Velocity

# Solve: To two significant digits, determine in Newtons the centripetal force of a 5 .0 kilogram rock moving with a tangental velocity of 3.5 meters per second around a circle of 1.5 meter radius.

* **Answer:** 41 Newtons (use F = (mv^2)/r)

# Solve: To two significant digits, calculate in Newtons the magnitude of the centripetal force produced by a 0.17 kilogram ball moving about a horizontal circular path with a radius of 1.6-meters at 2.5 meters per second.

* **Answer:** 0.66 Newtons (use F = (mv^2)/r)

# Solve: To two significant digits, calculate in Newtons the centripetal force required to keep a 15-kilogram mass moving in a horizontal circle with radius 3.0 meters and speed 5.0 meters per second.

* **Answer:** 130 Newtons (use F = (mv^2)/r)

# Solve: Maddie is spinning a 5.0 kilogram bucket attached to a string over her head in a horizontal circle with a speed of 12 meters per second. To two significant digits, calculate in Newtons the centripetal force given that the string is 1.25 meters long.

* **Answer:** 580 Newtons (use F = (mv^2) / r)

# Solve: To two significant digits, calculate in Newtons the centripetal force required to keep a 25-kilogram mass moving in a horizontal circle with radius 3.0 meters and speed 5.0 meters per second.

* **Answer:** 210 Newtons | (Use F = (mv^2) / r)

To two significant digits, calculate in meters per second the speed of a 4.5-kilogram mass moving in a horizontal circle as a result of a constant 7.5-newton force. The radius of the circular motion is 3.5 meters. Neglect friction.

**Answer:** 2.4 meters per second

To two significant digits, calculate in newtons the centripetal force acting on a 950 kg car that rounds a non-banked curve with a radius of 75 meters at a velocity of 25 meters per second.

* **Answer:** 7900 Newtons | (Use F = (mv^2) / r)

To three significant digits, determine in meters per second the maximum velocity around a non-banked curve of radius 150. meters with a coefficient of static friction of 1.60.

**Answer:** 48.5 meters per second

# Solve: This is a two-part question concerning a 4.0-kilogram toy car traveling clockwise at a constant speed of 6.0 meters per second in a horizontal circle with a radius of 12 meters. * Part 1: At a given point in time the car is traveling due east. In what direction is the net force acting on the car at this time? * Part 2: If the speed is doubled but the radius of the path remains the same, to two significant digits calculate in newtons the magnitude of the centripetal force acting on the car.

* **Answer 1:** South (always towards the center of the circle - in this case it's South if the tangential velocity is East.) * **Answer 2:** 48 Newtons (Use F = (mv^2)/r, result is 12. Doubling velocity results in a four-fold increase in force, therefore the force becomes 48 Newtons.)

# Solve: To two significant digits, calculate in newtons, the average net force necessary to accelerate a 950 kg car from rest to a speed of 4.5 meters per second in 5.0 seconds.

* **Answer:** 860 Newtons * Find the acceleration (change in velocity over the change in time). * Use Newton's Second Law (F = ma) to solve for the net force (F).

# Fill in the blank: The [BLANK] velocity is perpendicular to the centripetal force and the centripetal acceleration.

Tangential

Planetary Gravitation

# fSolve: A 2.5-kilogram box is placed at the top of a 3.5-meter-high ramp. To two significant digits, calculate in meters per second the speed of the box as it reaches the end of the frictionless plane.

* **Answer:** 8.3 meters per second

# Solve: To three significant figures, calculate in newtons the attractive force between two 6.35- kilogram bowling balls separated by a distance of 0.750 meters.

* **Answer:** 4.78 x 10^(-9) Newtons

A double star system has an average separation of 1.3 x 10^10 meters. To two significant digits, determine in kilograms the mass of one star given that both stars have the same mass and the force between the stars is 7.7 x 10^29 newtons.

**Answer:** 1.4 x 10^30 kilograms

Determine to three significant digits the force in newtons the gravitational force between a pair of 1550 kilogram objects separated by 1.75 meters.

**Answer:** 5.23 x 10^(-5)

To two significant digits, determine in Newtons the magnitude of the gravitational force between a 1,500 kilogram mass and a 3,500 kilogram mass separated by 2.5 meters.

**Answer:** 5.6 x 10^(-5) Newtons

To three significant digits, determine in meters per second the minimum velocity of a satellite that is orbiting the earth at an altitude of 150 kilometers above the surface.

**7820** meters per second

# Solve: A pair of stars, each with a mass of 2.0 x 10^30 kilograms, exert a force of 1.0 x 10^30 Newtons on each other. To two significant figures calculate in meters the distance between the two stars.

* **Answer:** 1.6 x 10^10 meters

# Solve: To three significant digits, determine in meters per second the orbital speed of a spacecraft on orbit about the earth at an altitude of 400. kilometers.

* **Answer:** 7680 m/s

# Solve: In terms of W, determine the weight of an astronaut on planet Q given the following: his weight on Earth is W; the radius of planet Q equals ¼ that of the Earth's radius; and the mass of planet Q equals 1/8 that of the Earth's mass.

* **Answer:** 2W

Assuming a circular orbit, to two significant digits, determine in meters per second the orbital speed of a satellite whose altitude is 36,000 kilometers above the surface of the earth.

* **Answer:** 3100 m/s

# Solve: To three significant digits, calculate in meters the radius of the orbit of a certain spacecraft in orbit about the earth given that the orbital period of the spaceship is 94.5 minutes.

* **Answer:** 6.87 x 10^6 meters | (Be sure to convert from minutes to seconds.)

# Solve: To two significant digits, calculate in **minutes** the orbital period of a certain spacecraft in a circular orbit given that the orbital altitude is 193 kilometers above the surface of the Earth.

* **Answer:** 88 minutes

Elon Musk has his Tesla Roadster launched into a circular heliocentric orbit of radius 200. million kilometers. To two significant digits, determine in days the orbital period for the Roadster, assuming the mass of the sun is 2.0 x 10^30 kilograms.

**Answer** 560 days

To two significant digits, determine in meters from the center of the Earth the radius of an orbit of a satellite with an orbital speed of 7700 meters per second. ## Footnote Topic: Gravitation

**6.7 x 10^6** meters

# Solve: To three significant digits, calculate in meters per second the orbital velocity of a spacecraft orbiting the Earth at an altitude of 450. kilometers.

**Answer**: 7650 m/s

# Solve: To three significant digits, determine in astronomical units the distance of Saturn from the Sun using the following data: * Distance of the earth from the sun: one AU * Orbital period of the earth: one year * Orbital period of Saturn: 29.4 years

* **Answer**: 9.53 A.U. * This is a Kepler's Third Law problem

Which one or ones of the following four statements are consistent with Kepler's laws of planetary motion? 1. The planets move at a constant speed around the Sun. 2. An imaginary line from a planet to the Sun sweeps out equal areas in equal time intervals. 3. The speed of a planet is directly proportional to the radius of the path of the motion. 4. The more massive the planet, the slower the planet moves around the Sun.

* **Answer:** 2. An imaginary line from a planet to the Sun sweeps out equal areas in equal time intervals.

# Solve: Emily has been tasked with designing a spacecraft to orbit at an altitude of 6780 kilometers from the center of the Earth. To two significant digits, determine in meters per second the minimum orbital velocity required to place the spacecraft on orbit.

* **Answer:** 7700 meters per second

# Solve: To three significant digits, determine the period in seconds for a satellite orbiting the earth at an altitude of 240. kilometers above the surface.

* **Answer:** 5350 seconds

# Solve: To two significant digits, determine in meters per second the velocity of a proton whose orbit has a radius of 0.250 meters in a magnetic field of 0.500 Tesla.

**Answer**: 1.2 x 10^7 m/s

To two significant digits, determine in Newtons the force on a 2.5 meter long wire that has a current of 5.0 amps that is embedded in a 3.5 Tesla magnetic field, given that the magnetic field is perpendicular to the wire.

* **Answer:** 44 Newtons

# Solve: To two significant digits, determine in **hours** the period of a satellite in a circular orbit located 20,200 kilometers above the surface of the earth.

* **Answer:** 12 hours

To two significant digits, determine in Teslas the magnitude of a magnetic field that forces an electron traveling at a speed of 1.7 x 10^8 meters per second into a circular orbit of radius 3.5 centimeters.

* **Answer:** 0.028 Teslas

To two significant digits calculate in newtons the force exerted on an electron moving at 42 meters per second parallel to a magnetic field whose strength is 347 teslas.

**Answer:** 0 Newtons

# Solve: To three significant digits, determine in astronomical units the radius of the orbit of a planet that has a period of 164.8 years.

* **Answer:** 30.1 A.U.

# Solve: On January 1, 2019, the New Horizons spacecraft flew by the most distant celestial body yet explored, Ultima Thule. This object has an average orbital radius of 44.6 AU, the radius of Earth’s orbit is 1.00 AU, and Earth’s orbital period is 1.00 years. To three significant digits, determine in years the orbital period of Ultima Thule.

* **Answer:** 298 years

# Solve: To two significant digits, calculate in seconds the period of an earth satellite orbiting at an altitude of 450 kilometers.

* **Answer:** 5600 seconds

Magnetism

# Solve: To two significant digits, determine in Teslas the magnitude of a magnetic field that produces a force of 170 Newtons on an electron whose speed is 2.7 x10^7 meters per second.

* **Answer:** 3.9 x 10^13 Teslas

# Solve: To two significant digits, determine in seconds the orbital period of an electron in a circular orbit about a magnetic field line of magnitude 0.25 T that has an orbital radius of 5.0 millimeters.

* **Answer:** 1.4 x 10^(-10) seconds | (Remember to convert millimeters to meters)

# Solve: To two significant digits, determine in meters the radius of the orbit of a proton about a 0.25 Tesla magnetic field line, given that the mass of the proton is 1.67 x 10-27 kilograms, if the proton is traveling at the speed of light.

* **Answer:** 13 meters | (The equation pictured is derived from mv^2/r = qvB.) ## Footnote (GPT does NOT like this problem, clearly.)

Work, Energy, & Power

# Solve: A student pushes a 7.5 kilogram box across the floor by applying a force of 22 Newtons. To two significant digits, determine the work in Joules done by the student if he pushes the box a distance of 4.0 meters.

* **Answer:** 88 Joules

# Solve: To two significant digits, calculate in joules the amount of energy required to lift the Avengers’ Helicarrier to a height of 2.5 kilometers, given that the mass of the Helicarrier is 1.2 x 10^8 kilograms.

* **Answer:** 2.9 x 10^12

# Solve: If the speed of an oxygen molecule is 400. meters per second, give to two significant digits the speed in meters per second of a hydrogen molecule at that same temperature.

* **Answer:** 1600 meters per second

Which one or ones of the following four statements are true? 1. When a force moves an object over a rough, horizontal surface at a constant speed, thework done against friction produces an increase in the object's internal energy. 2. During the time that a comet makes its closest approach to the sun, the kinetic energy is at a maximum and the potential energy is at a minimum. 3. As a ball falls freely (without friction) toward the ground, its total mechanical energy remains constant. 4. The potential energy stored in a compressed spring is to the change in the spring's length as the kinetic energy of a moving object is to the object's speed.

* **Answer:** All four statements are true.

At which point or points in the system will kinetic energy be at its maximum?

**Answer:** B

# Solve: To three significant digits, determine in meters the height of a roller coaster hill given that a 350. Kg cart has a speed of 22.0 meters per second at the bottom of the hill. Assume no energy losses.

* **Answer:** 24.7 meters

Neglecting friction, to two significant digits, determine in meters per second the velocity of a certain roller coaster at the bottom of the first drop, given that drop is 60. meters.

**Answer:** 34 meters per second

# Solve: A 2.2 x 10^-3 kilogram steel ball is fired vertically downward from a height of 15 meters at an initial speed of 12 meters per second. The steel ball strikes the ground and comes to rest at a depth of 0.25 meters. To two significant digits, calculate in Joules the change in mechanical energy of the steel ball relative to the ground.

* **Answer:** (-) 0.48 Joules * You can solve this with either just energy conservation or a combination of energy and kinematics. Either way, find the kinetic energy as the ball strikes the ground. That energy becomes zero as it slows to a stop. The difference is the answer. ## Footnote Note: The answer key says (-) 0.49, but I disagree

# Solve: To three significant digits, calculate in joules the kinetic energy of Aladdin and his magic carpet just before they strike the ground if they started from rest at a height of 100 meters with a combined mass of 65.0 kg. Neglect air resistance. | (Are they assuming that they just...drop? That's not very magic-like.)

* **Answer:** 6.37 x 10^4 Joules

# Solve: To two significant digits, calculate in joules the kinetic energy of a 2500-kilogram car that is traveling at a speed· of 115 kilometers per hour.

* **Answer:** 1.3 x 10^6 Joules * This one is straightforward. Just use the kinetic energy equation: (1/2) mv^2.

# Solve: A 15-kilogram steel block is released from rest at a height of 25 meters and slides down an incline to the bottom. The block has a speed of 18 meters per second at the bottom of the slide. To two significant digits calculate the percentage of energy dissipated during this event.

* **Answer:** 34%

# Solve: To two significant digits, determine in Newtons the magnitude of the average force necessary to stop a 15 gram projectile that is traveling at 250 meters per second, if the stopping distance is 20. centimeters.

* **Answer:** 2300 Newtons

# Solve: A worker carries a 150-newton box up a ramp that is inclined at 25 degrees with respect to the horizontal. To two significant digits calculate in joules the total **work** done on the box if the horizontal distance traveled is 31 meters.

* **Answer:** 2200 Joules * Remember, no matter if a box is pushed up a ramp or lifted directly to the top, the work is the same. Use tan25 = x/31 to find the height of the ramp, then just do Work = change in energy = mgh = (150 x 31tan(25)). * Work is the change in energy between the initial and final conditions. The box gained mgh joules of gravitational potential energy.

# Solve: A 27-kilogram crate is raised vertically to a height of 130 meters in 35 seconds. To two significant figures, calculate in watts the power expended in lifting the crate.

* **Answer:** 980 Watts

To two significant digits, determine in watts the required power it takes to move a box 25. meters given that the force used is 150 Newtons and it takes 7.0 seconds to move the box.

**Answer:** 540 Watts

# Solve: A winch is used to raise a 520 kilogram load of concrete blocks a vertical distance of 150 meters. To two significant digits, calculate in watts the minimum power of the winch motor if it takes 5.0 minutes to raise the load.

* **Answer:** 2500 Watts

# Solve: Kayla hangs a mass upon a vertical ideal spring. If the spring has an elastic potential energy of 70. Joules when extended to a distance of 0.75 meters, to two significant digits, determine in newtons per meter the spring constant of the system.

* **Answer:** 250 Newtons per meter

To two significant digits, calculate in newtons per meter the spring constant for an ideal spring that has a potential energy of 2.4 joules when being stretched 0.20 meters.

**Answer:** 120 Newtons per meter

# Solve: A 2.5-kilogram block is placed on a spring that has been compressed 12.0 centimeters. To two significant digits calculate in centimeters the vertical height above the fully extended spring reached by the block when the spring is released. The spring constant is 2400 newtons per meter. Neglect air resistance.

* **Answer:** 71 centimeters | (Is it 70 or 71 when rounded?)

# Solve: To two significant digits, calculate in Newtons per meter the spring constant of an ideal spring platform system when a 10. kilogram mass dropped from a height of 15 meters onto the system compresses the spring 35 centimeters.

* **Answer:** 24,000 Newtons per Meter

To two significant digits calculate in newtons per meter the spring constant of a spring that oscillates in simple harmonic motion with a period of 0.25 seconds when a 450-gram mass is attached.

**Answer:** 280 Newtons per meter

# Solve: A scale model of the Artemis 1 rocket is launched vertically upward with an initial speed of 195 meters per second. To two significant digits, calculate in meters the maximum height of the hobby rocket.

* **Answer:** 1900 meters

Momentum, Collisions, & Impulse

If the mass, m, of an object is related to its momentum, p, by the equation m = p/B, determine the physical quantity represented by B.

* **Answer:** Velocity * Momentum is mass times velocity (p = mv)

This quantity is momentum divided by velocity.

* **Answer:** Mass

This quantity is the product of the mass and linear velocity of a body.

**Answer:** Momentum

# Solve: Which of the following four are equal in terms of units? 1. impulse 2. change in momentum 3. momentum 4. inertia

**Answer:** 1, 2, and 3 (impulse, change in momentum, and momentum all have the same units.)

This is a two-part question. Part 1: Identify the collision where momentum is conserved, but total kinetic energy is not conserved. Part 2: Identify the collision where both kinetic energy and momentum are conserved.

**Answer:** Part 1: inelastic; Part 2: elastic

# Solve: A toy car with a mass of 1.5 kilograms has a speed of 4.3 meters per second. To two significant figures calculate in meters per second the speed needed for a 3 .5-kilogram toy car to have the same momentum as the first toy car.

* **Answer:** 1.8 meters per second

# Solve: To two significant digits, calculate in meters per second the change in speed for a 6.5-kilogram mass that has a 9.2-newton horizontal force applied to it for a period of 2.3 seconds. Neglect friction.

* **Answer:** 3.3 m/s * The image shows an alternate way to solve this, but I used Impulse = Force x time = change in momentum. Momentum is mass x velocity, so my equation was force x time = mass x velocity, and solve for velocity.

To the nearest whole number, determine in newtons the impact force of a body given that the impulse is 120 newton seconds over a period of 0.12 seconds.

* **Answer:** 1000 Newtons

To two significant digits calculate in Newtons the net force required to stop a 1500-kilogram car that accelerates from rest at 0.75 meters per second squared for a period of 1.25 seconds before it has an inelastic collision with a solid wall and comes to a stop in 0.25 seconds.

**Answer:** 5600 Newtons

# Solve: A 90-kilogram hunter is tied to a 450-kilogram polar bear. They are both standing on ice 60 meters apart. To the nearest whole number calculate in meters the distance the polar bear will travel when the hunter pulls the bear toward him at a constant speed.

* **Answer**: 10 meters | (This one's a weird conservation of momentum problem.)

# Solve: To two significant digits, determine in meters per second the speed of the wreckage when a 2500-kilogram car traveling at 25 meters per second collides with a 4500- kilogram stationary car. Assume a perfectly inelastic collision.

* **Answer:** 8.9 meters per second

# Solve: To two significant digits, determine in kilogram-meter per second the change in momentum of a 0.145-kilogram baseball thrown against a wall at 7.5 meters per second and returning in the direction from which it came at 4.5 meters per second.

* **Answer:** 1.7 (kilogram-meters per second)

# Solve: To three significant digits, calculate in meters per second the final speed of a pair of carriages with masses of 1.50 and 2.50 kilograms respectively given that the 1.50 kilogram carriage is moving to the right at 5.00 meters per second and the 2.50 kilogram carriage is moving 8.50 meters per second to the left. Assume the collision is perfectly inelastic and no energy losses.

* **Answer:** 3.44 (meters per second to the left)

# Solve: To three significant digits, calculate the final speed of a pair of bumper cars that collide inelastically given that the first car has a mass of 150. Kilograms and travels at 5.00 meters per second to the right and the second car has a mass of 100. Kilograms and travels to the left at 9.50 meters per second. Assume no energy losses.

* **Answer:** 0.800 (meters per second) ## Footnote (If the question wanted velocity, it would be -0.800 meters per second or 0.800 meters per second to the left. The question asks for speed, so just provide the magnitude and not the direction.)

Block A and Block B are traveling towards each other on a frictionless horizontal surface. Block A is traveling right at 3.0 meters per second and Block B is traveling left at 4.0 meters per second. To two significant digits, calculate in meters per second the final velocity of the system given that the two blocks stick together after colliding and the mass of Block A is four times the mass of Block B.

**Answer**: (+) 1.6 (meters per second), (to the) right ## Footnote (Note: must give the direction – judges can prompt for more information)

# Solve: To two significant digits, calculate in meters per second the combined speed of a pair of 75 kilogram bumper cars that collide head-on in a perfectly inelastic collision given that the two cars have speeds of 15 and 10. meters per second.

* **Answer:** 2.5 meters per second

A 2500-kilogram car traveling to the right at 25 meters per second has a perfectly inelastic collision with a 1000. kilogram car traveling to the left at 5.0 meters per second. To two significant digits, determine in meters per second the final speed of the combined cars.

* **Answer:** 16 meters per second

# Solve: To two significant digits, calculate in meters per second the combined speed of a pair of 235 kilogram bumper cars that collide head-on in a perfectly inelastic collision given that the two cars have speeds of 12 and 19 meters per second.

* **Answer:** 3.5 meters per second

# Solve: Calculate the final speed in terms of v0 for the following system. Block X is traveling horizontally along a frictionless track at a speed of v0 meters per second when it collides with and sticks to block Y that is initially at rest. Block X has mass M and block Y has mass 9M. | (Formatting: v0 here refers to initial velocity.)

* **Answer:** One-tenth v0

# Solve: To two significant digits, calculate in meters per second the recoil speed of a 6.0 kg rifle from which a 0.025 kg bullet is shot at a speed of 350 meters per second.

* **Answer:** 1.5 meters per second

Calculate to two significant digits the recoil velocity in meters per second of a 65-kilogram cannon which sits on a frictionless surface and shoots a 0.037 kilogram projectile with a velocity of 437 meters-per-second. ## Footnote (A 1996 question.)

**Answer:** -0.25 meters per second

# Solve: A 45-kilogram skater is standing at rest in a skating rink. To two significant digits calculate in meters per second the recoil speed of the skater if he throws a 0.25-kilogram ball horizontally at a speed of 32 meters per second. Neglect friction.

* **Answer:** 0.18 meters per second ## Footnote (The answer key says in big bold letters DO NOT ACCEPT -0.18)

# Solve: By what magnitude has the speed of an object changed if the mass of the object has remained constant but the momentum of the object tripled?

* **Answer:** Three (or tripled or three times) * momentum = mass * velocity

# Solve: Two eggs with equal mass are dropped simultaneously from the same height. Egg 1 hits the ground and breaks. Egg 2 lands on a foam pad, without bouncing, and remains intact. Fill in the blank with greater, less, or the same. Compared to the magnitude of the impulse on egg 1 as it lands, the magnitude on egg 2 as it lands is [BLANK].

* **Answer:** The same

By which factors will the force of gravity between two masses be affected if the distance between the two masses is increased by a factor of 3?

* **Answer:** One-ninth

The gravitational force of attraction between two objects would increase by which one of the following three? 1. doubling the distance between the objects only 2. doubling the mass of both objects & doubling the distance between the objects 3. doubling the mass of both objects only

* **Answer:** 3. Doubling the mass of both objects only

Simple Harmonic Motion

Fill in the blank with the missing three-word term: [BLANK] is linear motion in which the acceleration is propottional to the displacement from the equilibrium position and directed toward that position.

* **Answer**: Simple Harmonic Motion

# Solve: Fill in the blank. At the maximum displacement of an object in simple harmonic motion, the [BLANK] is also at a maximum.

* **Answer:** Acceleration

Electricity

# Provide the formula: Coulomb's Law

The force of attraction or repulsion between two point charges is directionally proportional to the product of the charges and inversely proportional to the square of the distance between them.

Definition of a Coulomb

A Coulomb is a unit of **electric charge**. One coulomb is equal to the electric charge delivered by a 1 ampere current in 1 second. The coulomb is **equal to 1 A·s**

# Solve: A physicist pets his cat and produces an excess positive charge of 3.00 coulombs on the cat. To three significant digits, determine in Newtons per coulomb, the electric field produced by the cat at a distance of 0.250 meters from the cat.

* **Answer:** 4.32 x 10^11 Newtons per Coulomb

To two significant digits calculate in newtons the magnitude of the force acting on a particle with a charge of -0.030 coulombs when it is placed 1.5 meters from a particle with a charge of -0.015 coulombs.

* **Answer:** 1.8 x 10^6 ## Footnote (Answer Key: "Do not accept -1.8 x 10^6)

To three significant digits calculate in coulombs the amount of charge that moves through a circuit if the current is 15.0 amperes over a period of 0.350 seconds.

* **Answer:** 5.25 Coulombs

To one significant digit, determine in meters the separation between a pair of protons, each having a charge of 1.6 x 10-19 coulombs given that the force of repulsion is 25 Newtons.

**Answer:** 3 x 10^(-15) meters

An unknown charge is located 10. centimeters from a 5.0 coulomb charge. To two significant digits, calculate in coulombs the magnitude of the unknown charge given that the force between the two charges is 6.75 x 1013 Newtons.

**Answer:** 15 Coulombs

Calculate the exact potential difference across an 8-ohm resistor that draws 2 coulombs of charge every 4 seconds.

**Answer:** 4 (V)

A 2-ohm resistor is in series with two other 2-ohm resistors that are in parallel with each other. Calculate in ohms the exact equivalent resistance of the circuit.

**Answer:** 3 Ohms

To two significant digits, calculate in ohms the resistance of a light bulb which draws 2.0 amps when attached to a 5.0-volt power source.

**Answer:** 2.5 Ohms

A 1.5-ohm resistor and a 2.5-ohm resistor are connected in series with a battery. If the current through the circuit is 3.5 amps, to two significant figures, calculate in volts the voltage of the battery.

* **Answer:** 14 Volts

To two significant digits, calculate in amperes the current in a circuit in which a 16 ohm and 20. ohm resistor are connected in series to a 4.0 V power source.

**Answer:** 0.11 Amperes

Compute the resistance in ohms of a wire in a 100 watt light bulb designed to operate in a 110 volt circuit. ## Footnote (A 1996 question.)

**Answer:** 121 Ohms

Calculate exactly the equivalent resistance of a 15-ohm resistor and a 30-ohm resistor when connected in parallel.

**Answer:** 10 Ohms

To two significant digits, calculate in amperes the current in a circuit that has resistors of 10.,15, and 20. ohms connected in series across a source of 24 volts.

**Answer:** 0.53 Amperes

To two significant digits, calculate in amperes the current in a circuit that has resistors of 25 and 75 ohms connected in parallel across a source of 220 volts.

**Answer:** 12 Amperes

To two significant digits, calculate in amperes the current of a circuit constructed with a 12-volt battery, a 2.0-ohm resistor, and a 4.0-ohm resistor in series with a parallel branch containing a 6.0-ohm resistor and an 8.0-ohm resistor.

**Answer:** 1.3 Amperes

To three significant digits, determine the value of the resistance with its uncertainties if voltage (V) is 18.0 ± 0.2 volts and current (I) is 4.50 ± 0.3 amps. Uncertainties are given to one significant figure.

**Answer:** 4.00 +/- 0.3 Ohms

To three significant digits, calculate in amps the current of three resistors of 60.0 ohms, 30.0 ohms, and 120.0 ohms that are connected in parallel across a 90.0 volt difference in potential.

**Answer:** 5.25 Amperes

To two significant digits, determine in amps the current in a circuit having a pair of 125 Ohm resistance light bulbs connected in parallel, given that the circuit in turn is connected to a 120 volt source.

**Answer:** 1.9 Amps

To two significant digits, determine in ohms the resistance of a certain electric appliance given that the power delivered is 1200 watts at 240 volts.

**Answer:** 48 Ohms

Fill in the blank in the following sentence with greater, less or same. A 2.0 ohm resistor and a 4.0 ohm resistor are connected in parallel across a 7.5 volt source. Compared to the power dissipated by the 2.0 ohm resistor, the power dissipated by the 4.0 ohm resistor is [BLANK].

* **Answer:** Less

To two significant digits, calculate in meters the necessary length of an aluminum wire in order for it to have the same 1.50-ohm resistance as that of a 12-meter length of copper wire. Both wires have the same cross-sectional area. The resistivity of copper is 1.69 x 10^(-8) and the resistivity of aluminum is 2.75 x 10^(-8).

**Answer:** 7.4

Calculate the exact number of amperes for the total current flow in an ideal circuit composed of three 75-ohm resistors in parallel connected to a 100-volt battery.

**Answer:** 4 Amperes

This is a two-part question. To the nearest tenth, calculate in amperes the current in a circuit connected to a 6.0-volt power supply that contains one 3.0-ohm resistor, one 5.0-ohm resistor, and one 7.0-ohm resistor when: Part 1: the resistors are connected in series with the power supply. Part 2: the resistors are connected in parallel with the power supply.

* **Answer Part 1:** 0.4 Amperes * **Answer Part 2:** 4.1 Amperes

Fill in the two blanks. A sphere with a net charge of -4.8 x 10·19 coulombs has an excess of (blank) (blank).

**Answer:** Three electrons

# Solve: A pair of electrons are separated by a distance of 0.25 millimeters. To two significant digits, calculate in Newtons the magnitude of the force between the electrons.

* **Answer:** 3.7 x 10^(-21) Newtons

To two significant digits, calculate in newtons the force between a pair of electrons separated by a distance of 0.25 meters.

**Answer:** 3.7 x 10^(-27) Newtons

To two significant digits, determine in meters the distance between a pair of electrons given that the electrons exert a force of 0.25 newtons upon each other.

* **Answer:** 3.0 x 10^(-14) Newtons

To two significant digits, determine in Newtons per coulomb the magnitude of the electric field produced by an electron that produces a force of 900. Newtons on a test plate.

**Answer:** 5.6 x 10^21 (Newtons per Coulomb)

To two significant digits, calculate in Coulombs the electric charge that passes through a light bulb in one minute given that the current through the bulb is 2.5 amperes.

* **Answer:** 150 Coulombs

To two significant digits calculate in volts the potential difference of a set of parallel plates that is being used as a cell in a battery if the electric field between the plates is 3500 Newtons per Coulomb and the plate separation is 3.5 centimeters.

**Answer:** 120 Volts

# Solve: To two significant digits, determine in meters the separation between the plates of a parallel plate capacitor that has a length of 0.025 meters and a width of 0.010 meters. The capacitor has a capacitance of 1.5 x 10-12 Farads. The permittivity of free space is 8.85 x 10-12 coulombs per newton meter squared.

* **Answer:** 1.5 x 10^(-3) (meters)

# Solve: To two significant digits, determine in Newtons the magnitude of the electrical force between a pair of electrons separated by a distance of 10.0 millimeters

* **Answer:** 2.3 x 10^(-24)

To two significant digits, determine in Newtons the electrical force between two electrons separated by 0.025 meters.

* **Answer:** 3.7 x 10^(-25) Newtons

# Solve: To two significant digits calculate in newtons the magnitude of the electric force between a positive 15-coulomb charge and a negative 65-coulomb charge when they are in a vacuum separated by a distance of 12 centimeters.

* **Answer:** 6.1 x 10^14 Newtons

To two significant digits, determine in Newtons the electrostatic force between a pair of electrons separated by 0.50 centimeters.

**Answer:** 9.2 x 10^(-24) Newtons

Steven is conducting an experiment where he determines the magnitude of the force per unit length between a pair of parallel current carrying wires. One wire has a current of 50 Amps and the other has a current of 10 Amps. To one significant digit, determine in Newtons per meter the force per unit length given that the wires are separated by 0.25 meters. μ = 4π × 10^(−7) Tm/A

**Answer:** 4 x 10^(-4) Newtons per meter

# Solve: Which one or ones of the following four combinations would produce no change in the electrostatic force between these two spheres? 1. doubling q on one sphere while doubling r 2. doubling q on one sphere while halving r 3. halving q on both spheres while halving r 4. doubling q on both spheres while doubling r

* **Answers:** * 3. halving q on both spheres while halving r AND * 4. doubling q on both spheres while doubling r

# Solve: In terms of F, give the force between two electrostatic charges when the distance is tripled if a force of F originally existed between the two point charges.

* **Answer:** F / 9 (or "F divided by nine")

# Solve: Two point charges are positioned such that the distance between them is 4.0 centimeters. By what factor will the mutual force between the two charges change when they are moved to a point where the separation distance is 2.0 centimeters?

* **Answer:** (A factor of) 4

Waves

Given that an electric guitar is generating a sound of constant frequency, an increase in which one of the following four sound wave characteristics would result in an increase in loudness? 1. amplitude 2. wavelength 3. speed 4. period

* **Answer:** 1. Amplitude * The amplitude of a sound wave is directly related to its loudness. When the amplitude increases, the sound energy increases, and we perceive this as an increase in loudness. The other characteristics listed—wavelength, speed, and period—are not directly related to the loudness of the sound.

Which one or ones of the following four does a photon *not* possess? 1. Energy 2. Mass 3. Weight 4. Momentum

**Answer:** 2 and 3 (mass and weight)

Fill in the blank. The [BLANK] of a photon is inversely proportional to the photon's wavelength.

* **Answer:** Momentum * Momentum = (Planck's Constant *h*) / (Wavelength) | (I would have said "frequency," but it's not on the answer key.)

# Solve: To two significant digits calculate in hertz the frequency of a wave that completes one vibration as it moves a distance of 2.0 meters at a speed of 22 meters per second.

* **Answer:** 11 Hertz

# Solve: To two significant digits, calculate respectively in hertz and seconds the frequency and period of a wave having a speed of 240 meters per second and a wavelength of 3.2 meters.

* **Answers:** 75 Hertz and 0.013 seconds

# Solve: A pipe open at both ends has a fundamental frequency of 320 Hz when the speed of sound in air is 331 m/s. To two significant digits, determine the fundamental frequency in Hz of this pipe when the speed of sound in air is increased to 367 m/s due to a rise in the temperature of the air.

* **Answer:** 350 Hertz | (354.8 rounded to 350 Hz) ## Footnote According to quantum mechanics, all objects have a de Broglie wavelength. The wavelength is only noticeable for particles with very small masses, such as electrons. For macroscopic objects, the wavelength is so much smaller than the object's physical size that the wave-like behavior goes unnoticed.

# Solve: The speed of sound in a 375 meter metal pipe is given by "v". A worker at one end of the pipe strikes the pipe with a sharp blow. A worker at the other end of the pipe hears two sounds, one from the sound of the blow traveling through the pipe and one from the sound of the blow traveling through air. To three significant digits, calculate in meters per second the speed of sound through the metal pipe given that the time between which the worker heard the two sounds was 1.03 seconds.

* **Answer:** 5920 meters per second

# Solve: To three significant digits, determine in meters the length of a tube, closed at one end, that produces resonance at its fundamental frequency of 256 hertz. Assume the speed of sound is 331 meters per second.

* **Answer:** 0.323 (meters)

# Solve: A closed pipe has a length of 0.505 meters. To three significant digits, determine in meters per second the speed of sound in air given that the third harmonic of a 512 hertz tuning fork is recorded.

**Answer**: 345 meters per second ## Footnote Remember: The speed of sound is about 343 meters per second, but changes in different temperatures.

# Solve: To two significant digits, determine in hertz the frequency of the third harmonic of a 0.50 meter long closed pipe, given that the the speed of sound is 340. meters per second.

* **Answer**: 510 Hertz * I think the easiest way to solve this is to look at the chart below. For the first harmonic, or the fundamental frequency, the wavelength is 4L (where L is the length of the pipe.) * Using (speed of sound) = (wavelength * frequency), we get 340 = (4 x 0.5) x frequency, so the frequency is 340 / 2. * Then, to get the third harmonic, we just multiply that by three to get 510 Hz.

# Solve: To three significant digits, calculate in hertz the frequency produced by the third harmonic of a 0.650 meter long closed pipe, given that the speed of sound is 345 meters per second.

* **Answer:** 398 Hertz * I think the easiest way to solve this is to look at the chart below. For the first harmonic, or the fundamental frequency, the wavelength is 4L (where L is the length of the pipe.) * Using (speed of sound) = (wavelength * frequency), we get 345 = (4 x 0.650) x frequency, so the frequency is 345 / 2.6. * Then, to get the third harmonic, we just multiply that by three to get 398 Hz.

# Solve: To three significant digits, determine in hertz the observed frequency of an air horn that has a stationary frequency of 256 hertz, given that the horn is moving toward a stationary observer at 125 meters per second and the speed of sound is 345 meters per second.

* **Answer** 401 Hertz

# Solve: To three significant digits, determine in he11z the observed frequency of a horn with an initial frequency of 256 hertz approaching a stationary observer at 150. meters per second. Assume the speed of sound is 340. meters per second.

* **Answer:** 458 Hertz ## Footnote A Doppler effect question.

# Solve: A certain string has a mass of 25.0 grams and a length of 1.25 meters. To three significant digits, determine in meters per second the speed of the standing wave if the tension in the string is 45.0 Newtons.

* **Answer:** 47.4 meters per second ## Footnote (This one is unusual because it addresses how tension in a string affects the speed of the wave.)

To two significant digits, determine in Newtons the tension in a massless non-extendible string connecting a 15 kilogram mass on a frictionless inclined plane with an angle of 30. degrees with respect to the horizontal given that the string is routed over an ideal pulley to a 10. kilogram mass that hangs vertically from the pulley.

**Answer:** 88 (Newtons)

A pair of masses is connected by a massless, non-extendable string draped over an ideal frictionless pulley. The 10.0 kilogram mass is located on a frictionless horizontal table and is connected via the string to a 15.0 kilogram mass. The 15.0 kilogram mass is gently released and allowed to fall. To three significant digits, determine in meters per second squared the magnitude of the acceleration of the system.

**Answer:** 5.88 meters per second squared

# Solve: Give to three significant digits in meters the de Broglie wavelength of a 40.0-gram rock with a speed of 40.0 meters per second. | (This is a strange one from 2009.)

* **Answer:** 4.14 x 10^(-34) meters ## Footnote According to quantum mechanics, all objects have a de Broglie wavelength. The wavelength is only noticeable for particles with very small masses, such as electrons. For macroscopic objects, the wavelength is so much smaller than the object's physical size that the wave-like behavior goes unnoticed.

According to Albert Einstein, which one or ones of the following four will increase if you increase the brightness of a beam of light without changing its color? 1. the frequency of the photons 2. the speed of the photons 3. the energy of each photon 4. the number of photons | (Another one from 2009.)

* **Answer:** 4. The number of photons

# Misc: The amount of energy expended when a force of 16 ounces acts through a distance of 12 inches is a *foot-pound.*

Rotational Kinematics

“Give me a place to stand and with a lever I will move the whole world.” A workman uses a lever of 5 meters in length to lift a 500 kg object. The fulcrum is placed 1.0 meter from the object. To the nearest whole number, calculate in newtons the minimum effort force required.

**Answer:** 1,225 Newtons

# Solve: A potter’s wheel is a solid cylinder, where I= ½ mr^2, with a mass of 5.00 kilograms and a radius of 0.900 meters which is initially rotating with an angular speed of 7.00 radians per second. To three significant digits, calculate in radians per second the new angular speed of a potter’s wheel clay system when a 2.10 kilogram sample of clay is initially at rest and is dropped at a radius 0.500 meters onto the wheel.

* **Answer:** 5.56 radians per second

# Solve: To two significant digits, calculate in meters per second the final speed of a uniform sphere of radius R that rolls from rest without slipping down an incline plane of 30° for a length of 6.0 meters. I equals (2/5)mR^2 for the sphere. | ("I" is the moment of inertia.)

* **Answer:** 6.5 meters per second

# Solve: A 10.0 kilogram mass is hung from the end of a massless meter stick and a 5.00 kilogram mass is hung from the opposite end. To three significant digits, determine in centimeters the distance of the balancing point relative to the 10.0 kilogram mass.

* **Answer:** 33.3 centimeters

# Solve: A student is performing an experiment in which she has a 0.5 kilogram object attached to a string that runs through a tube with a velocity of 9 radians per second located 1.5 meters from the tube. To two significant digits, determine the angular velocity in radians per second if the distance to the tube is shortened to 0.9 meters. | (Huh? An object on a string that runs through a tube?)

* **Answer:** 25 radians per second | (I'm really having trouble visualizing this one.)

Optics

Identify the dimensionless number that describes how a ray of light propagates through a medium.

**Answer:** Index of Refraction

The ratio of the speed of light in a vacuum to the speed of light in a substance is called the [BLANK - three word term ] for the substance.

* **Answer:** Index of Refraction

Which one of the following four phenomena causes chromatic aberration to occur when polychromatic light passes through a lens? 1. diffraction and refraction 2. diffraction and reflection 3. dispersion and refraction 4. dispersion and reflection

**Answer:** 3. Dispersion and Refraction

# Solve: To two significant digits, calculate in centimeters the radius of curvature for a certain spherical mirror that has an object distance of positive 750 centimeters and an image distance of positive 25.4 centimeters.

* **Answer:** 49 centimeters

A monochromatic ray of light passes from air into water. Which one or ones of the following four characteristics of the ray will not change? 1. frequency 2. period 3. wavelength 4. speed

* **Answer:** 1 (frequency) and 2 (period)

What is the index of refraction of water?

**Answer:** 1.33

To the nearest whole number, calculate in degrees the angle of refraction for a ray of monochromatic light traveling in air that enters a liquid at an angle of 45 degrees. The wavelength of the light is 5.9 x 10^(-7) meters, and the index of refraction of the liquid is 1.4.

**Answer:** 30 degrees

To three significant digits, determine by Brewster's Law the index of refraction of a substance if the reflected ray of light is completely polarized and reflects at an angle of 53° in air.

**Answer:** 1.33

# Solve: To three significant digits, determine in meters per second the speed of light traveling in a substance whose index of refraction is 1.28.

* **Answer:** 2.34 x 10^8 meters per second

To three significant digits, determine in centimeters the focal length of a certain thin lens whose index of refraction is 1.52 with radii of curvatures r1 = 10.0 centimeters and r2 = 5.00 centimeters.

**Answer:** -19.2 centimeters

Sarah is designing a lens where the object will be located 250 centimeters in front of the lens and she requires the image to be formed 10. centimeters behind the lens. To two significant digits, determine in centimeters the radius of curvature.

**Answer:** 19 centimeters

# Solve: To two significant digits calculate in meters per second the speed of light in a block of glass with an index of refraction of 1.7.

* **Answer:** 1.8 x 10^8 meters per second

To the nearest one-tenth of one degree, determine the critical angle for light passing from a diamond into air given the index of refraction for diamond is 2.42.

**Answer:** 24.4 degrees

# Solve: To two significant digits calculate in centimeters the radius of curvature for a spherical mirror that has an object distance of 550 centimeters and an image distance of 35 centimeters.

* **Answer:** 66 centimeters

# Solve: This is a three-part question concerning a 10.0-centimeter object that is placed 90.0 centimeters in front of a concave mirror with a focal length of 30.0 centimeters. Part 1: To two significant digits, calculate in centimeters the location of the image in front of the mirror. Part 2: To two significant digits, calculate in centimeters the height of the image. Part 3: Is the object inverted or upright?

* **Answer:** Part 1: 45 centimeters * **Answer:** Part 2: 5.0 centimeters * **Answer:** Part 3: inverted

# Solve: To three significant digits, determine in meters the object distance given that the image distance is 3.70 meters in front of a certain parabolic mirror with a focal length of 2.50 meters.

* **Answer:** 7.71 meters

# Solve: Which one of the following four situations is true for a virtual image produced by a lens? 1. The image is projected. 2. The image distance s is positive. 3. The projected image is magnified. 4. The image is erect.

* **Answer:** 4. The image is erect.

Thermal Physics

# Solve: To two significant digits, determine in degrees Celsius the change in temperature of a certain mass of water as it flows over a waterfall given that water has a specific heat of 4,186 joules per kilogram degree Celsius, and the mass falls a distance of 120 meters.

* **Answer:** 0.28 degrees Celsius

# Solve: Which one or ones of the following four will not promote the rate of heat flow from burner to food if cooking is done using an aluminum pan over an electric burner? 1. increase pan bottom thickness 2. increase pan bottom area 3. increase burner temperature 4. decrease height of pan sides

* **Answer:** 1. Increase pan bottom thickness

# Solve: A copper ring with a mass of 18 grams is dropped from the top of a 6-story building and lands in a bucket containing 0.50 kilograms of water. The average height of one story of this building is 3.5 meters. The specific heat of liquid water is 4.184 joules per gram–degrees Celsius. To two significant digits calculate in degrees the change in temperature of the water assuming that all of the mechanical energy from the ring is converted into heat energy.

* **Answer:** 0.0018 degrees Celsius

# Solve: If a certain star’s distance from the Earth tripled, the star’s brightness would: A. increase by a factor of 3 B. decrease by a factor of 3 C. increase by a factor of 9 D. decrease by a factor of 9

* **Answer:** D. Decrease by a factor of nine | (Due to the inverse square law for light.)

Fluid Dynamics

# Solve: The water tower that supplies sound suppression water to Space Launch Complex 39B is 90 meters tall. Given that the top of the water within the tank descends at two meters per second, to one significant digit, determine in meters per second the speed of the water at the outlet at the bottom of the tank.

* **Answer:** 40 meters per second

# Solve: A ship collides with an iceberg and a circular hole with an area 150 square centimeters is ripped in the hull. The hole is located 2.00 meters below the water line. To two significant digits, determine the amount of time in seconds that the crew has to abandon the ship given that it can take on 100.0 cubic meters of water before it sinks. Neglect friction and assume the water flows straight in.

**Answer:** 1100 seconds

To two significant digits, determine in meters per second the speed of a jet of an ideal fluid whose initial speed is 10. meters per second given the fluid is forced through a nozzle that is one fourth of the original diameter.

* **Answer:** 160 meters per second

Physics: Practice Questions Flashcards

Make Sir Isaac proud. (327 cards)