Question

12. Through what angle in degrees does a 31 rpm record turn in 0.27 s

13. Starting from rest, the same torque is applied to a solid sphere and a hollow sphere. Both spheres have the same size and mass, and both are rotating about their centers. After some time has elapsed, which sphere will be rotating faster?

answer choices:

a. hollow sphere

b. They will be rotating equally fast

c. solid sphere

14. In movies, it often happens that when a person is struck with a bullet, they are thrown backwards by the impact. Would the person be thrown backwards at greater speed if the bullet remains inside the person or if it passes through the person and emerges on the other side?

answer choices:

a. Person's speed would be higher if the bullet gets stuck

b. Person's speed would be the same either way

c. Person's speed would be higher if the bullet emerges

15. An Atwood machine (such as the one shown) is constructed using a massive pulley of fixed mass and size. Which of the following shapes would you choose for the pulley if you want the machine to accelerate as fast as possible when released?

answer choices:

a. Hollow Sphere

b. Acceleration would be the same for all of these

c. Solid Cylinder

d. Solid Sphere

16. A picture is shown of a woman holding a shopping bag in each hand. Assuming that the bags have equal weight and her arms are the same length, in which case is the torque exerted by the bag's weight about her corresponding shoulder higher in magnitude?

answer choices:

a. They exert equal torque

b. Red bag exerts more torque

c. White bag exerts more torque

17. An object is in circular motion in the xy plane. The center of the circle is at the origin (x=0, y=0). At a certain moment in time, its centripetal acceleration points in the +x direction. Which of the following can we say is true about its motion?

answer choices:

a. It is traveling in a counterclockwise circle

b. The x component of its position negative

c. The y component of its position is positive

d. It is speeding up

e. The y component of its position is negative

f. The x component of its position positive

18. In the golf swing, the head of the golf club can be visualized as making a circular path (red) around the golfer's torso. This circle is tilted an angle A from the vertical as shown.

If the head of the club maintains a constant speed during the swing, at what point in the swing is the tension in the club the highest?

answer choices:

a. the tension in the club is the same throughout the swing

b. the highest point in the swing

c. the lowest point in the swing

d. when the club is horizontal (level with his torso)

19. A ball of mass m strikes a wall traveling at speed v in the +x direction. It bounces off the wall, rebounding at speed v/2 in the -x direction. What is the magnitude of the impulse imparted to the ball by the wall?

answer choices:

a. 3mv/4

b. 0

c. 5mv/4

d. mv/2

e. mv

f. 3mv/2

20. A man (mass m) is standing on a raft (mass 2m) in the middle of the ocean. Assume the water is perfectly at rest and frictionless. The man begins to walk at speed v in the +x direction. What will be the x component of the raft's velocity?

answer choices:

a. -v/2

b. v/2

c. 0

d. v

e. -v/3

f. -v

g. v/3

21. The following image shows a very expensive marble "gravity defying" cantilever table. The question you probably have is "Will this table tip over if I put something heavy on it?" According to the manufacturer's website, it is 152 pounds in weight. The tabletop is L=26.6 inches in length. The width of the base of support is w=10.4 inches. Assume that nearly all the mass is in the support so that its center of mass is in the middle of the base. A schematic sketch is included to help you visualize the dimensions.

If you placed a block on the edge of the table as shown, what mass (in kg) would tip the table over? (Hint: Consider the base of support.)

22. An object is in circular motion in the xy plane. The center of the circle is at the origin (x=0, y=0). It is traveling in a clockwise circular path at constant speed. What is the direction of its tangential acceleration?

answer choices:

a. +x

b. Cannot be determined

c. -y

d. +y

e. 0

f. -x

Answer 1

12. Through what angle in degrees does a 31 rpm record turn in 0.27 s

w = 31 rpm = 31 * 2 / 60 = 3.246 radians

so,

distance moved in given time , = 3.246 * 0.27 = 0.8765 radians

or

= 50.22 degree

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13)

for same applied torque, the acceleration will depend on moment of inertia. The object with lower moment of inertia will move faster.

for solid sphere, I = (2/5)mr²

for hollow sphere, I = (2/3)mr²

so,

As inertia is less for solid sphere, it will move faster

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14)

when bullet gets stuck , all the momentum of bullet must be conserved, so person will move faster

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15)

I will use solid sphere as it has lowest moment of inertia among the given.

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