PHY EXAM MCQ CHAP 8,9,11

A solid sphere of radius R rotates about a diameter with an angular speed ω. The sphere then collapses under the action of internal forces to a final radius R/2. What is the final angular speed of the sphere?

4w

Consider the following three objects, each of th e same mass and radius: (1) a solid sphere (2) a solid disk (3) a hoop All three are released from rest at the top of an inclined plane. The three objects proceed down the incline undergoing rolling motion without slipping. In which order do the objects reach the bottom of the incline?

1,2,3

Complete the following statement: When a net torque is applied to a rigid object, it always produces a

Change in angular velocity

Two points are located on a rigid wheel that is rotating with decreasing angular velocity about a fixed axis. Point A is located on the rim of the wheel and point B is halfway between the rim and the axis. Which one of the following statements concerning this situation is true?

Both points have the same instantaneous angular velocity.

Complete the following sentence: The operation of a hydraulic jack is an application of

Pascal's principle

A long thin rod of length 2L rotates with a constant angular acceleration of 8.0 rad/s2 about an axis that is perpendicular to the rod and passes through its center. What is the ratio of the angular speed (at any instant) of a point on the end of the rod to that of a point a distance L/2 from the end of the rod?

1:1

A solid sphere rolls without slipping along a horizontal surface. What percentage of its total kinetic energy is rotational kinetic energy?

29%

A long thin rod of length 2L rotates with a constant angular acceleration of 8.0 rad/s2 about an axis that is perpendicular to the rod and passes through its center. What is the ratio of the centripetal acceleratio n of a point on the end of the rod to that of a point a distance L/2 from the end of the rod?

2:1

A long thin rod of length 2L rotates with a constant angular acceleration of 8.0 rad/s2 about an axis that is perpendicular to the rod and passes through its center. What is the ratio of the tangential acceleration of a point on the end of the rod to that of a point a distance L/2 from the end of the rod?

2:1

A long thin rod of length 2L rotates with a constant angular acceleration of 8.0 rad/s2 about an axis that is perpendicular to the rod and passes through its center. What is the ratio of the tangential speed (at an y instant) of a point on the end of the rod to that of a point a distance L/2 from the end of the rod?

2:1

Which one of the following statements concerning a completely enclosed fluid is true?

Any change in applied pressure produces an equal change in pressure at all points within the fluid.

What happens when a spinning ice skater draws in her outstretched arms?

Her moment of inertia decreases causing her to speed up.

Which one of the following statements concerning the moment of inertia I is false?

I depends on the angular acceleration of the object as it rotates.

Which one of the following statements most accurately describes the center of gravity of an object?

It is the point from which the torque produced by the weight of the object can be calculated.

Two uniform solid spheres, A and B have the same mass. The radius of sphere B is twice that of sphere A. The axis of rotation passes through each sphere. Which one of the following statements concerning the moments of inertia of these spheres is true?

The moment of inertia of A is one-fourth that of B.

A solid sphere and a hollow sphere each of mass M and radius R are released at the same time from the top of an inclined plane. Which one of the following statements is necessarily true?

The solid sphere will reach the bottom first.

A rigid body rotates about a fixed axis with a constant angular acceleration. Which one of the following statements is true concerning thetangential acceleration of any point on the body?

The tangential acceleration depends on the change in the angular velocity.

Three blocks, labeled A, B, and C, are floating in water as shown in the drawing. Blocks A and B have the same mass and volume. Block C has the same volume, but is submerged to a greater depth than the other two blocks. Which one of the following statements concerning this situation is false?

The volume of water displaced by block A is greater than that displaced by block B.

Complete the following statement: A body is in translational equilibrium

if it is either at rest or moving with constant velocity.

A ball of mass M moves in a circular path on a horizontal, frictionless surface. It is attached to a light string that passes through a hole in the center of the table. If the string is pulled down, thereby reducing the radius of the path of the ball, the speed of the ball is observed to increase. Complete the following sentence: This occurs because

the angular momentum of the ball is conserved.

A hollow cylinder of mass M and radius R rolls down an inclined plane. A block of mass M easily slides down an identical inclined plane. Complete the following statement: If both objects are released at the same time from the top of their inclined planes,

the block will reach the bottom first.

Consider the following four objects: a hoop, a flat disk, a solid sphere, and a hollow sphere. Each of the objects has mass M and radius R. The axis of rotation passes through the center of each object, and is perpendicular to the plane of the hoop and the plane of the flat disk. Which of these objects requires the largest torque to give it the same angular acceleration?

the hoop

Which equation is valid only when the angular measure is expressed in radians ?

w= v_t/r