Final

Question 1

A person pushes two boxes with a horizontal 100 N force on a frictionless floor, as shown in the figure (Figure 1). Box A is heavier than box B

Answer 1

Boxes A and B push on each other with equal forces of less than 100 N

Question 2

A person pushes horizontally with constant force P on a 270 N box resting on a frictionless horizontal floor. Which of the following statements about this box is correct?

Answer 2

The box will accelerate no matter how small P is.

Question 3

Two carts, one twice as heavy as the other, are at rest on a horizontal frictionless track. A person pushes each cart with the same force for 3.00s. If the kinetic energy of the lighter cart after the push is K , the kinetic energy of the heavier cart is

Answer 3

1/2 K

Question 4

An object traveling at speed V/2 in a circle of radius 2R has an acceleration a. If both speed and radius are doubled, the new acceleration will be

Answer 4

2a

Question 5

An object of mass M suspended by a spring vibrates with a period T. If this object is replaced by one of mass 4M, the new object vibrates with a period

Answer 5

2T

Question 6

Three books are at rest on a horizontal table, as shown in the figure, the net force on the middle book is

Answer 6

0N

Question 7

If vector A has unity magnitude and makes an angle of 60∘ with the +x axis, then the x and y components of A are

Answer 7

Ax=1/2 , Ay=√3/2

Question 8

A ball is thrown horizontally from the top of a building and lands a distance d from the foot of the building after having been in the air for a time T and encountering no significant air resistance. If the building were twice as tall, the ball would have

Answer 8

been in the air a time T√ 2.

Question 9

A mass on a spring oscillates with a period T. If both the mass and the force constant of the spring are doubled, the new period will be

Answer 9

T

Question 10

Two masses, M and 8 M, are at rest on a horizontal frictionless table with a compressed spring of negligible mass between them. When the spring is released,

Answer 10

The two masses receive equal magnitudes of momentum & The lighter mass gains more kinetic energy than the heavier mass.

Question 11

An object with mass M suspended by a spring vibrates with frequency f. When a second object is attached to the first, the system now vibrates with frequency f/2.00. The mass of the second object is

Answer 11

3 M

Question 12

Two balls are dropped from the top of the Leaning Tower of Pisa. The second ball is dropped a fraction of a second after the first ball. As they continue to accelerate to the ground, the distance between them will

Answer 12

Increase

Question 13

For each of two objects with different masses, the gravitational potential energy is 85.0 J. They are released from rest and fall to the ground. Which of the following statements is or are true? (More than one statement may be true.)

Answer 13

Both objects will have the same kinetic energy when they reach the ground & Both objects will accelerate toward the ground at the same rate.

Question 14

A worker pushes horizontally on a 2000-N refrigerator on a kitchen floor with a force of 28.0 N.

Answer 14

The person always feels a 28.0 N push from the refrigerator.

Question 15

Two small objects of equal weight are attached to the ends of a thin weightless bar that spins about an axis perpendicular to the bar at its center. Each mass is a distance d from the axis of rotation. The system spins at a rate so that its kinetic energy is K. If both masses are now moved closer in so that each is d /7 from the rotation axis, while the angular velocity does not change, the kinetic energy of the system will be

Answer 15

1/49 K

Question 16

A pendulum on earth swings with angular frequency ω . On an unknown planet, it swings with angular frequency ω/ 2. The acceleration due to gravity on this planet is

Answer 16

g/4

Question 17

A segment A of wire stretched tightly between two posts a distance L apart vibrates in its fundamental mode with frequency f. A segment B of an identical wire is stretched with the same tension, but between two different posts. You observe that the frequency of the fourth harmonic of wire B is the same as the fundamental frequency of wire A. The length of wire B must be

Answer 17

4L

Question 18

A ball is thrown directly upwards with a velocity of + 14.0 m/s. At the end of 2.80 s , its velocity will be closest to

Answer 18

-14 m/s

Question 19

Your boat departs from the bank of a river that has a swift current parallel to its banks. If you want to cross this river in the shortest amount of time, you should direct your boat

Answer 19

perpendicular to the current.

Question 20

In which of the following collisions would you expect the kinetic energy to be conserved?

Answer 20

Two asteroids collide by a glancing blow, but do not actually hit each other, their only interaction being through gravity & Two cars with springlike bumpers collide at fairly low speeds.

Question 21

String A weighs one-third as much as string B. Both strings are thin and light and have the same length. If you hang equal weights at the bottom of each of these strings, the ratio of the speed of waves on string A to the speed of waves on string B will be

Answer 21

vA/vB=√3

Question 22

You slam on the brakes of your car in a panic and skid a distance d on a straight and level road. If you had been traveling twice as fast, what distance would the car have skidded under the same conditions?

Answer 22

4d

Question 23

A spiral spring is compressed so as to add U units of potential energy to it. When this spring is instead stretched two-thirds of the distance it was compressed, its remaining potential energy in the same units will be

Answer 23

4 U /9.

Question 24

The system shown in the figure is released from rest, there is no friction between B and the tabletop, and all of the objects move together.(Figure 1). What must be true about the friction force on A ?

Answer 24

It acts to the right on A

Question 25

If vector A has components Ax = -3.00 and Ay = -4.00, then the magnitude of A is

Answer 25

5

Question 26

A vector is directed at an angle θ above the +x axis, pointing into the first quadrant. If the x component of this vector is 15 m , the magnitude of the vector is

Answer 26

greater than 15 m .

Question 27

When a wheel turns through one complete rotation, the angle (in radians) that it has turned through is closest to

Answer 27

6

Question 28

A weightless spring scale is attached to two equal weights as shown in the figure.(Figure 1)

Answer 28

W (not sure cuz was weird on mine)

Question 29

A woman normally weighs 123 lb. She is standing on a spring scale in an elevator that is traveling downward, but slowing up.

Answer 29

The scale will read more than 123 lb .

Question 30

An organ pipe open at one end, but closed at the other, is vibrating in its fundamental mode, producing sound of frequency 1000 Hz. If you now open the closed end, the new fundamental frequency will be

Answer 30

2000 Hz

Question 31

Two lumps of clay having equal masses and speeds, but traveling in opposite directions, collide and stick together. Which of the following statements about this system of lumps must be true?

Answer 31

The momentum of the system is conserved during the collision, The two masses lose all their kinetic energy during the collision & the velocity of the center of mass of the system is the same after the collision as it was before the collision.

Question 32

Which of the following statements is true for an inelastic collision?

Answer 32

Momentum is conserved, but kinetic energy is not conserved & the amount of momentum lost by one object is the same as the amount gained by the other object.

Question 33

Which of the following equations correctly expresses the relation between vectors A, B , C, and D shown in the figure?

Answer 33

A +B −C −D =0

Question 34

An omnidirectional loudspeaker produces sound waves uniformly in all directions. The total power received by a sphere of radius 2.10 m centered on the speaker is 300 W. A sphere of radius 4.20 m will receive a total power of

Answer 34

300 W

Question 35

Vector A⃗ has a magnitude of 3.00 and is directed parallel to the negative y-axis and vector B⃗ has a magnitude of 3.00 and is directed parallel to the positive y-axis. Determine the magnitude and direction angle (as measured counterclockwise from the positive x-axis) of vector C, if C =A −B .

Answer 35

C = 6.00; θ = 270˚

Question 36

A small car collides head-on with a large SUV. Which of the following statements concerning this collision are correct?

Answer 36

Both vehicles are acted upon by the same average force during the collision & Both vehicles undergo the same change in momentum

Question 37

A frog leaps vertically into the air and encounters no appreciable air resistance. Which statement about the frog’s motion is correct?

Answer 37

On the way up, on the way down, and at the highest point its acceleration is 9.8 m/s2 downward.

Question 38

A bicycle wheel rotating at a rate of 18 rad/s begins to accelerate at a rate of 5 rad/s2. After 3 seconds the rate of rotation will be

Answer 38

33 rad/s

Question 39

A person listening to a siren from a stationary police car observes the frequency and wavelength of that sound. The car now drives rapidly away from the person.

Answer 39

The wavelength of the sound the person observes will be longer than it was, and the frequency will also be lower than it was.

Question 40

A thin uniform bar has a moment of inertia I about an axis perpendicular to it through its center. Part complete
If both the mass and length of this bar are halved, its moment of inertia about the same axis will be

Answer 40

1/8 I

Question 41

You are standing between two stereo speakers that are emitting sound of wavelength 9.00 cm in step with each other. They are very far apart compared with that wavelength. If you start in the middle and walk a distance x directly toward one speaker, you observe that the sound from these speakers first cancels when x is equal to

Answer 41

2.25cm

Question 42

Which of the following statements about work is or are true? (More than one statement may be true.)

Answer 42

Negative net work done on an object always reduces the object’s kinetic energy & The formula W=Fdcosθ can be used only if the force is constant over the distance

Question 43

Traffic noise on Beethoven Boulevard has an intensity level of 80 dB; the traffic noise on Mozart Alley is only 60 dB. Compared to the sound intensity on Beethoven Boulevard, the sound intensity on Mozart Alley is

Answer 43

100 times lower.

Question 44

Cart A, of mass 2 kg , is initially moving to the left and collides with cart B, which has a mass of 5 kg and is initially at rest. (See the figure below. (Figure 1)). After the collision, cart A will

Answer 44

move back to the right (Idk cuz was being weird on mine)

Question 45

If the distance d (in meters) traveled by an object in time t (in seconds) is given by the formula d=A+Bt^2 , the SI units of A and B must be

Answer 45

meters for A and m/s^2 for B

Question 46

A woman wearing spiked shoes pushes two crates across her frictionless horizontal studio floor. (See (Figure 1).) If she exerts a horizontal force of 53 N on the smaller crate, then the smaller crate exerts a force on the larger crate that is closest to

Answer 46

44N

Question 47

Two uniform solid spheres of the same size, but different mass, are released from rest simultaneously at the same height on a hill and roll to the bottom without slipping. Which of the following statements about these spheres are true?

Answer 47

Both spheres reach the bottom at the same time & both spheres arrive at the bottom with the same forward speed

Question 48

Two balls are dropped at the same time from different heights. As they accelerate toward the ground, the distance between them will

Answer 48

remain constant

Question 49

A golfer tees off and hits the ball with a mighty swing. During the brief time the golf club is in contact with the ball,

Answer 49

the ball pushes just as hard on the club as the club pushes on the ball.