Topic 1 - Motion, Forces, Newton’s Laws & Stopping Distance Flashcards by Emma Jensen

Are force and velocity vector or scalar? (1)

Force = vector
Velocity = vector

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What’s a vector quantity? (1)

It has direction and size

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Calculate the acceleration of a train, at 34seconds and 26m/s. (3)

Acceleration = change in velocity/time (1)
26-14/34 (1)
0.35m/s^2 (1)

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What decreases the stopping distance of a car? (1)
Had more passengers
Had worn tires
Needed new breaks
Was travelling more slowly

Was travelling slower (1)

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A car travelling at 15m/s comes to rest in a distance of 14m when the brakes are applied.
Calculate the deceleration of the car. (3)

Acceleration = change in velocity/2xdistance (1)
15/2x14 (1)
8.04m/s^2 (1)

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Which of these is a vector? (1)
Mass
Force
Energy
Distance

Force

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Which of these is a vector? (1)
Energy
Force
Mass
Work

Force

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How would the line look in a speed time graph for: (2)
The car is standing still
The car is accelerating
The car is decelerating
The car is travelling at a constant speed

The car is standing still - horizontal line at 0m/s
The car is accelerating - line with a +ve gradient
The car is decelerating - line with a -ve gradient
The car is travelling at a constant speed - horizontal line not at 0m/s

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Which of these speeds foul be normal for a person walking? (1)
0.1m/s
1.0m/s
10m/s
100m/s

1.0m/s

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A car with a mass of 1800 kg is accelerating at 1.2 m/s2. Calculate the force used to accelerate the car. (2)
Use the equation force = mass × acceleration

1800x1.2 (1)
2200 (1)

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A box falls to a hard floor and crumples a little before it comes to rest.
The momentum of the box just before it hits the floor is 8.7 kg m/s.
The box comes to rest 0.35 s after it first hits the floor.
Calculate the magnitude of the force exerted by the floor on the box. (2)

Force = change in momentum/time OR 8.7/0.35 (1)
25N (1)

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The gravitational field strength on the Moon = 1.6 N/kg.
The mass of a rock on the Moon is 6.0 kg.
Calculate the weight of this rock on the Moon. (3)
Use the equation weight = mass × gravitational field strength

6 x 1.6 (1)
9.6 (1)
Newtons (1)

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A student investigates the effect of a crumple zone on the force exerted during a collision.
The student has one trolley with a spring at the front and another trolley without a spring. After a trolley is released, it accelerates down a slope and bounces off a rigid wall.
The speed of a trolley can be measured just before a collision with the wall and just after a
collision with the wall.
The silver foils are connected to a millisecond timer.
The silver foils make contact with each other during the collision, so the time they are in
contact can be read from the millisecond timer.
Explain how the student could investigate the effect of a crumple zone on the average force
exerted during the collision.
Your explanation should include:
• how to determine the force (you may wish to refer to an equation from
the list of equations at the end of this paper)
• how the effect of crumple zones may be shown in the investigation
• precautions that may be necessary to achieve accurate results.

Determining force:
Use of F=change in momentum/time or F=ma
Mass of trolley needed
And times during impact

Showing effect of crumple zone:
Experiment repeated with & without the spring
Note difference in contact times
Use of spring as crumple zone
With spring, time for contact greater, less impact force

Precautions/controls:
Times repeated & average taken
Careful controls, e.g. same starting position/same angle of slope/release without pushing etc.

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A toy car has a mass of 0.10 kg.
The toy car accelerates at 2.0 m/s^2.
Calculate the force producing this acceleration. (3)
Use the equation F = m × a

0.1x2 (1)
0.2 (1)
Newtons (1)

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Correct equation relating force, mass & acceleration

Force = mass x acceleration

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A cyclist has a mass of 70 kg.
Calculate the force needed to accelerate the cyclist at 2.0 m/s^2.
State the unit. (2)

140 (1)
Newtons (1)

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A plane has an upwards force of 8.4kN and a downwards force of 7.5kN. Determine the size and direction of the resultant vertical force on the aeroplane. (2)

0.9 (1)
Up (1)

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The mass of an aeroplane is 750 kg.
Calculate the change in GPE of the aeroplane as it descends from 1300m to the ground. (2)
Gravitational field strength (g) = 10 N/kg

750 x 10 x 1300 (1)
9 800 000J (1)

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Figure 13 shows 2 objects before and after they collide. Explain how momentum is conserved in the collision. Use Newton’s 3rd law and Newton’s 2nd law in your answer. It can be written as Force=change in momentum/time
(6)

Q-> R Q-> R->

Momentum = mass x velocity
Action & reaction are equal & opposite
Force of R on Q = force of Q on R
Change in momentum of Q/time= change in momentum of R/time
Time of collision same for both
No overall change in moment
R accelerates because of force from Q
Transfer of momentum between Q & R

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The Asteroid Belt is part of our Solar System.
Vesta is an asteroid in the Asteroid Belt.
Vesta has an orbital speed of 1.9 × 10^4 m/s.
Vesta travels a distance of 2.2 × 10^12 m when it orbits the Sun once.
Calculate the time taken for Vesta to orbit the Sun once. (2)

Time = 2.2 × 10^12 / 1.9 × 10^4 (1)
1.2 x 10^8 (1)

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A car travelling at 15 m/s comes to rest in a distance of 14 m when the brakes are applied.
Calculate the deceleration of the car. (3)

Acceleration = change in speed^2 / 2xtime (1)
15^2/2x14 (1)
8.04 m/s (1)

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The force that keeps an object moving in a circular path is known as the… (1)

Centripetal force

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The diagram shows a G-machine. Which direction does the centripetal force on the astronaut (A) act? (1)

O—————A

Towards the centre of the circle (o)

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Increasing the speed of rotation of a G-machine will …………………………………………
the centripetal force on the astronaut. (1)

Increase

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The greater the radius of rotation, the ......................................... the centripetal force on the astronaut. (1)

Smaller

The G-machine is rotated by an electric motor. The following statements explain how the motor creates a turning force. The statements are in the wrong order. M – The magnetic field interacts with the magnetic field of the permanent magnets. N – A magnetic field is created around the coil. O – The power supply applies a potential difference across the coil. P – This creates a force that makes the coil spin. Q – A current flows through the coil. Arrange the statements in the correct order.

O – The power supply applies a potential difference across the coil. Q – A current flows through the coil. N – A magnetic field is created around the coil. M – The magnetic field interacts with the magnetic field of the permanent magnets. P – This creates a force that makes the coil spin.

An electric motor produces a turning force. Give 2 ways of increasing the turning force.

Increase the current/p.d. (1) Increase the number of turns of the coil (1) Increase the area of the coil (1) Increase the (strength of the permanent) magnetic field (1)

The athlete throws a heavy metal ball attached by a wire to a handle. The hammer thrower swings the hammer round in a circle before letting go. He swings the hammer slowly at first and then faster. Complete the following sentence. (1) As the speed of the swing increases, the centripetal force on the hammer ___________.

Increases

Finish the sentence by selecting an option The centripetal force is provided by the ________ Air resistance Gravitational force Tension in the wire

Tension in the wire

A hammer thrower swinging a hammer anticlockwise in a circle. The athlete let’s go of the hammer, which direction does the hammer move? (1) Person / A B/ X D C

A skateboarder moving in a circular path. Another skateboarder has a smaller mass. Complete the following sentence: She uses the same part of the ramp at the same speed. The force which allows her to move in a circular path will need to ________. If she goes faster, this resultant force will need to ________. Decrease Stay the same Increase

Decrease Increase

On their website, the managers of a skateboard park give the following information about some of the ramps where skateboarders move in a circular path. Name of ramp / Inside radius of the ramp in metres Bull pit / 6 Dragon’s den / 11 Tiger cage / 8 Witch’s cauldron / 7 A skateboarder uses each ramp at the same speed. Name & explain the ramp where the resultant force on the skateboarder will need to be the greatest.

Bull pit, because it has the smallest inside radius.

The hammer throw is an athletic event. The athlete throws a heavy metal ball attached by a wire to a handle. The hammer thrower swings the hammer round in a circle before letting go. He swings the hammer slowly at first and then faster. Complete the following sentence by choosing an option. As the speed of the swing increases, the centripetal force on the hammer _________. decreases does not change Increases

Increases

A racing car can accelerate by changing ________. It’s direction only It’s speed only either its direction or its speed

Either it direction or it’s speed

A racing car moves round a circular part of a racetrack. A force acts on the racing car. The force is towards the centre of the circular part of the racetrack. Complete the following sentences: The force is caused by _________. (Electrostatics/friction/gravity) The force is a _______. (Centripetal force/circular force/perpendicular force) If another racing car has a greater mass and travels at the same speed around the same racetrack, then the force will need to _______. (Decrease/stay the same/increase) When the racing car goes faster, the force will need to ________. (Decrease/stay the same/increase)

Friction Centripetal Increase Increase

This is an item from a newspaper: At last night’s meeting, one local resident said, “The racetrack will be noisy but motor racing leads to safety improvements in all our cars.’’ “We’ll need better brakes. Motor racing encourages speeding and leads to more accidents’’, said another. Most of the residents were against the plan to build a racetrack. Do you agree with most of the residents?

(Yes) noisy (1) It disturbs people living nearby (1) (Yes) encourages people to drive faster (1) Which makes road accidents more serious/likely (1) (No) leads to improvements in safety features (1) Such as better breaks (1) (Not sure) noisy (1) But new tires have a better grip (1)

The drawing shows a set of carriages on a roller coaster. The carriages are moving upwards in a nearly circular path at a constant speed. Complete the following sentences: The carriages will accelerate because of a change in their ___________. (Direction/mass/speed) The resultant force which causes the carriages to accelerate is the _______ force. (circular/centripetal/gravity) The resultant force will need to be greater if the _______. (mass of the passengers is greater/radius of the circle is greater/speed of the carriages is less)

Direction Centripetal Mass of passengers is greater

Malik uses a camera to photograph the Moon. Complete the sentences with these words: (converging, diverging, image, longer, object, real, shorter , virtual) In a camera a ................. lens is used to produce an .................. of an .................... on a film. The ...................... is smaller than the ..................... and it is a ...................... distance from the lens.

Image Object Image Object Shorter

The Moon moves in a nearly circular path around the Earth. What is the name of the force which causes the Moon to move around the Earth? ......................... (1) In which direction does this force act? ............................... (1)

Earth’s gravity/centripetal (1) Towards the centre of the earth (1)

A force is needed to make a car change direction when it goes round a bend. What is the name of this force and where does it act? ............................ (2) The force needed is greater if the .............. of the car is greater and the ................. of the bend is smaller. (2)

Centripetal force Mass/speed/momentum

Which of these is a vector: Energy Momentum Power Speed

Momentum

The rate of doing work is called _________. (Energy/power/momentum/speed)

Power

A javelin has a mass of 0.8 kg. In one throw, the javelin left the athlete’s hand at a velocity of 25 m/s. Calculate the kinetic energy of the javelin as it left the athlete’s hand. State the unit. (3)

1/2 x 0.8 x 25^2 (1) 250 (1) Joules (1)

A javelin has a mass of 0.8 kg. In one throw, the javelin left the athlete’s hand at a velocity of 25 m/s. State the amount of work done by the athlete on the javelin to get it to a velocity of 25 m/s. (1)

250

A good javelin thrower will try to extend their arm as much as possible before releasing the javelin. Explain why this allows them to do more work on the javelin. (2)

Work done = force x direction (1) (Force) used over a long distance (1)

Which one of these can be measured in Joules per second? (1) Energy Momentum Power Work

Power

Complete the sentence using words below. (1) The ................ transferred to the cart is equal to the ............... done on the cart. (Energy/momentum/power/work)

Energy Work

The child and cart have a total mass of 50 kg. They travel at a velocity of 4 m/s. Calculate the momentum of the child and cart. (2)

50 x 4 (1) 200 (1)

The child and cart have a total mass of 50 kg. They travel at a velocity of 4 m/s. The father applies a steady force for a time of 1.5 s. The momentum of the child and cart increases by 450 kg m/s. Calculate the force which the father applies. (2)

450/1.5 (1) 300 (1)

A mother and her daughter are stationary on an ice rink. The mother and daughter push each other away. They move in opposite directions with different speeds. Explain why they have different speeds (3)

Mother and daughter have different mass (1) Momentum is conserved/is 0 to start with (1) Both have same size momentum (after push) (1) So speed of the daughter is greater than that of the mother (1)

A car is travelling along a level road. When the velocity of the car is constant, the force of friction on it is _______. (1) zero greater than the driving force smaller than the driving force the same size as the driving force

The same size as the driving force

A car accelerates in a straight line. Its average acceleration is 12 m/s^2. Calculate the increase in velocity of the car in 4.0 s. (3)

Change in speed = acceleration x time (1) 12 x 4 (1) 48 (1)

This table shows data about 2 cars. car - mass - time taken to reach 30 m/s from rest family car - 1400 kg - 10 s sports car - 600 kg - 5 s The owner of the family car claims that although the sports car has greater acceleration, it produces a smaller accelerating force than his family car. Explain how these figures support his claim.

Acceleration of sports car is 2x than that of family car OR the time for the sports car to reach 30m/s is half the time it takes for the family car to do so (1) Mass of sports car is less than half of the family car (1)

After going to the shops, a car driver places a bag of shopping on the passenger seat. During the journey home, the driver has to use the brakes to stop very suddenly. The driver is wearing a seat belt. Explain what happens next to the car, the driver and the shopping bag. (6)

Brakes apply a force to the car The force from the brakes makes the car decelerate/lose velocity A force also acts on the driver Driver decelerates at the same rate as the car Driver stays in driving seat Driver moves slightly as the belt stretches Small/no horizontal force acts on the shopping bag Shopping bag continues at similar/same velocity Until the shopping bag hits dashboard/falls off seat

A ball is dropped. Explain why the ball does not bounce back to its original height. (2)

Energy is lost (1) In collision with ground/air resistance (1)

A proton collides with a helium nucleus. The table gives some information about before and after the collision. proton: KE (arbitrary units) 12.5 (before) 4.5 (after) helium nucleus: KE (arbitrary units) 0 (before) 8 (after) Use information from the table to show that the collision is elastic. (2)

Total KE before the collision is 12.5 (12.5+0) (1) Total KE after the collision is 12.5 (4.5+8) (1)

State the name of one device that can be used to accelerate protons to very high speeds. (1)

Cyclotron

A bullet is moving towards a wooden block. The bullet is moving with a velocity of 170 m/s. The mass of the bullet is 0.030 kg. Show that the momentum of the bullet is about 5.0kg m/s. (1)

Momentum = 0.03 x 170

A bullet is moving towards a wooden block. The bullet is moving with a velocity of 170 m/s. The mass of the bullet is 0.030 kg. Its momentum is 5.1. The bullet collides with the wooden block and sticks in it. The bullet and the wooden block move off together. The mass of the wooden block is 0.80 kg. Calculate the velocity of the wooden block and bullet immediately after the collision. (3)

Mass of wooden block+bullet = 0.8+0.03 = 0.83 5.1 = 0.83 x velocity (1) Velocity = 6.1m/s (1)

What’s an in elastic collision? (2)

Kinetic energy isn’t conserved (1) Lost KE appears as heat/sound. (1) Momentum is conserved (1)

An electron and a positron collide and annihilate each other. 2 photons are produced. Explain why two photons must be produced, rather than just 1. (2)

Momentum must be conserved (1) So must have positive & negative momentum (1)

Calculate the minimum total energy of the photons produced when an electron and positron collide. Use the equation E = mc^2 mass of an electron = 9.1 × 10–31 kg speed of light = 3.0 × 108 m/s

2 x (9.1 x 10^-31) x (3 x 10^8)^2 (1) 1.6 x 10^-13 (1)

Calculate the resultant force of 500N forward and 300N backwards. (2) and state the direction. (1)

500 - 300 (1) 200 (1) Forwards (1)

The unit for GPE is _____. A J N W

The mass of a water skier is 54 kg. At the top of the jump, she is 5 m above the water level. Calculate the amount of GPE she gains in rising 5 m. Gravitational field strength = 10 N/kg (2)

54 x 10 x 5 (1) 2700 (1)

When a water skier reaches the top of a ramp, she lets go of the rope. Describe the energy changes that happen between the skier leaving the ramp and reaching the top of the jump.

Some KE at the ramp (1) Is transferred to GPE at the top (1) Still has some KE at the top (1) Some energy lost due to air resistance (1)

The mass of the car is 625 kg. Calculate the weight of the car. (2) gravitational field strength = 10N/kg

625 x 10 (1) 6250 (1)

Forces act on objects when they fall through the air. There are 2 forces acting on this ball as it falls through the air. Other than the weight, which forces are acting on the ball? (2)

Air resistance (1) Upwards (1)

After a short time the ball falls at a steady speed. The forces acting on the ball are now ................ . The acceleration of the ball is now ................. . (Balanced/changing/greater/smaller/zero) (2)

Balanced (1) Zero (1)

Which of these is a scalar? Acceleration Force Mass Velocity

Mass

In a vacuum, all bodies falling towards the Earth’s surface have the same ________. (Acceleration/Force/Mass/Velocity)

Acceleration

The water drop falls to the ground, 13m below, in 1.7s. Calculate the average speed of the drop while it is falling. (2)

13/1.7 (1) 7.6 (1)

A tank is a long way above the ground. It drips water at a steady rate. Explain why the drops which are near to the ground are an equal distance apart but the drops which have just started to fall are not. (6)

Drops near the top are accelerating Due to force of gravity Travel a greater distance in given time There’s air resistance on the drops as they fall This increases with velocity Resultant force is downward This reduces the resultant force Eventually resultant force is zero Drops have reached terminal/maximum velocity Drops at the bottom are all travelling at terminal velocity So travel same distance in a given time

A car accelerates at a constant rate of 1.83 m/s^2 along a flat straight road. The force acting on the car is 1.870 kN. Calculate the mass of the car. (3) Give your answer to 3 significant figures.

Mass = force / acceleration (1) 1870 / 1.83 (1) 1020 (1)

A car accelerates at a constant rate of 1.83m/s^2 The car accelerates from rest for 16 s. Calculate the speed of the car after 16 s. (3)

Change in speed/time = acceleration (1) 0+1.83x16 (1) 29.3 (1)

2 students are investigating reaction times. Student B supports his left hand on a desk. Student A holds a ruler so that the bottom end of the ruler is between the finger and thumb of student B. When student A releases the ruler, student B catches the ruler as quickly as he can with his left hand. The investigation is repeated with the right hand of student B. Give a reason why it is better to have the 0 cm mark at the bottom of the ruler rather than at the top. (1) Give a reason why two students are needed for this investigation. (1)

So that you can get a direct reading. (With calculation) If student B drops the ruler, they wouldn’t really be measuring their reaction time, as they know when the ruler will be dropped.

Which of these results are anomalous? 10.1, 25.5, 18.4, 14.6, 11.7, 14

25.5 is the anomalous result (1) Because it’s much further away from the mean than the other results (1)

Give two ways that some students can improve the quality of their data, other than ignoring anomalous results. For the reaction times experiment with rulers. (2)

Taking more readings (1) A 3rd person could also measure reaction times (1)

Describe how the students could develop their investigation (on reaction time with rulers) to investigate how reaction time changes with another variable. (2)

Using a larger group of students (1) And measure how their reaction time varies with age/height (1)

The student investigates the extension of the spring using 6 different weights. The results are shown below. weight (N) - extension (mm) 0.20 - 4.0 0.40 - 8.0 0.60 - 12.0 0.80 - 16.0 1.00 - 20.0 1.20 - 24.0 A student writes this conclusion: ‘The extension of the spring is directly proportional to the weight stretching the spring.’ Comment on the student’s conclusion. (3)

Equal increments of mass/force/weight cause equal increments of extension When the weight doubles from 0.2 to 0.4, the extension also doubles, from 4 to 8 (3)

The mass of a car is 1200kg. Calculate the resultant force on the car required to produce an acceleration of0.8 m/s^2.

Mass = 1200x0.8 (1) 960 (1)

A car, travelling at 20 m/s, with just the driver inside takes 70 m to stop in an emergency. The same car is then fully loaded with luggage and passengers as well as the driver. Explain why it will take a different distance to stop in an emergency from the same speed. (6)

It has a greater mass Greater kinetic energy/momentum Experiences the same breaking distance Requires a greater breaking force (than available) to stop (in the same distance) Has a smaller acceleration/deceleration Takes longer to get to rest (from a given speed) Travels a greater distance in this time Needs to do more work with the same amount of force F=ma Work done=Fxd

Andrew skis down a hill. Andrew starts from the top of the hill and his speed increases as he goes downhill. He controls his speed and direction by using his skis. He brings himself to a stop at the bottom of the hill. Describe the energy changes that happen between starting and stopping. (3)

GPE transferred to KE (1) Energy transferred as heat/sound during descend (1) Chemical energy transferred to heat energy in Andrew (1) Energy dissipated on stopping (1)

Andrew skis down a slope. His mass is 67 kg. Show that his momentum is about 2000 kg m/s when his velocity is 31 m/s. (2)

67 x 31 (1) 2077 (1)

Andrew falls over when his momentum is 2000kgm/s. After he falls over, he slows down by sliding across the snow. It takes 2.3 s for his momentum to reduce to zero. Calculate the average force on Andrew as he slows down. (2)

2000/2.3 (1) 870 (1)

Andrew is not injured by the fall when skiing even though he was moving quickly. Use ideas about force and momentum to explain why he is not injured. (2)

Force on Andrew is quite small (1) Because impact time is small (1) The acceleration/deceleration is quite small (1) Because impact distance is far (1)

The driver’s thinking distance is most likely to increase when _______. the driver is tired there is ice on the road the car is heavier the car moves at a slower speed

The driver is tired

A car has a mass of 800 kg. It has a velocity of 3.0 m/s. Calculate the momentum of the car. (2)

800 x 3 (1) 2400 (1)

The braking force on another car is 600 N. The force acts for a distance of 15 m. Calculate the work done by the braking force. (2)

600 x 15 (1) 9000 (1)

The work done by the brakes during braking is equal to _________. (1) the energy transferred the stopping distance the acceleration the thinking distance plus braking distance

The energy transferred

Some students investigate the speed of cars. They measure the time it takes each car to travel a distance of 80 m. State two measuring instruments the students should use. (2)

Stopwatch (1) Measuring wheel/tape (1)

David runs in a race. Explain why his average speed is less than his top speed. (2)

Speed changes (1) Because he’s slower to begin with/faster in the end (1)

Explain the difference between velocity and speed (2)

Velocity is a vector (1) Whereas speed is not (1)

The graph shows how Christine’s velocity changes from the time she leaves the plane until she reaches terminal velocity. (A positive curve that levels off) Explain, in terms of forces, why her velocity changes as shown in the graph.

Forces acting: Weight down Air resistance up Forces during fall: Weight constant Air resistance increases With speed Resultant force = W-R Effects on shape of graph: At start, resultant force is large, so gradient is steep Mid resultant force decreasing, so gradient decreases Terminal velocity, resultant force is 0, so 0 gradient

The resultant force on the car will be zero when the car is _______. (1) accelerating decelerating changing velocity moving at a constant velocity

Moving at a constant velocity

Explain why the units of acceleration are m/s^2 (2)

Velocity/speed measured in m/s (1) Divided by time in seconds (1)

When block is moving upwards at a constant velocity, the resultant force on the block is _______. (1) (It’s lifted by a crane) upwards and equal to its weight downwards and equal to its weight upwards and more than its weight zero

Zero

Topic 1 - Motion, Forces, Newton’s Laws & Stopping Distance Flashcards

(97 cards)