Physics Final Exam Chapter 5-6 quizzes

You are standing on a skateboard, initially at rest. A friend throws a very heavy ball towards you. You can either catch the object or deflect the object back towards your friend (such that it moves away from you with the same speed as it was originally thrown). What should you do in order to MINIMIZE your speed on the skateboard? a. Catch the ball. b. Deflect the ball. c. Your final speed on the skateboard will be the same regardless whether you catch the ball or deflect the ball. d. There is not enough information given to determine an answer.

A) Catch The Ball

An airplane starts from rest at the end of a runway and begins accelerating. The tires of the plane are rotating with an angular velocity that is uniformly increasing with time. On one of the tires, Point A is located on the part of the tire in contact with the runway surface and point B is located halfway between Point A and the axis of rotation. Which one of the following statements is true concerning this situation? a. Both points have the same instantaneous velocity. b. Each second, point A turns through a greater angle than point B. c. Both points have the same tangential acceleration. d. Both points have the same centripetal acceleration.

a. Both points have the same instantaneous velocity.

Two children are riding on a merry-go-round. Child A is at a greater distance from the axis of rotation than child B. Which child has the larger linear displacement? a. Child A b. They have the same non-zero linear displacement. c. Child B d. They have the same zero linear displacement.

a. Child A

An artillery shell explodes in midair and breaks up into many fragments. Which of the following statements are true regarding conditions immediately before and immediately after the explosion: I. The total momentum of the fragments is equal to the original momentum of the shell. II. The total kinetic energy of the fragments is equal to the original kinetic energy of the shell. a. Statement I only b. Statement II only c. Both Statement I and Statement II d. Neither statement is true.

a. Statement I only

A force is applied to a doorknob. This force will be most effective in causing the door to rotate when which of the following is true? a. The direction of the force is at an angle of 90o with respect to the door. b. The lever arm is perpendicular to the door. c. The lever arm length is zero meters. d. The lever arm is parallel to the direction of the force.

a. The direction of the force is at an angle of 90o with respect to the door.

Which of the following statements about the moment of inertia is false? a. The moment of inertia depends on the angular acceleration of the object as it rotates. b. The moment of inertia depends on the location of the rotation axis relative to the particles that make up the object. c. Of the particles that make up an object, the particle with the smallest mass may contribute the greatest amount to the moment of inertia. d. The moment of inertia depends on the orientation of the rotation axis relative to the particles that make up the object.

a. The moment of inertia depends on the angular acceleration of the object as it rotates.

An object is rolling, so its motion involves both rotation and translation. Which of the following statements must be true concerning this situation? a. The total mechanical energy is equal to the sum of the translational and rotational kinetic energies and the gravitational potential energy of the object. b. The translational kinetic energy may be 0 joules. c. The gravitational potential energy must be changing as the object rolls. d. The rotational kinetic energy must be constant as the object rolls.

a. The total mechanical energy is equal to the sum of the translational and rotational kinetic energies and the gravitational potential energy of the object.

Because Earth's orbit is slightly elliptical, Earth actually gets closer to the Sun during part of the year. When Earth is closer to the Sun its orbital speed is a. greater than when Earth is farthest away from the Sun. b. less than when Earth is farthest away from the Sun. c. sometimes greater sometimes smaller than when Earth is farthest away from the Sun. d. the same as when Earth is farthest away from the Sun.

a. greater than when Earth is farthest away from the Sun.

Which of the following quantities is equal to the change in momentum of an object during a collision? a. impulse b. net force c. work d. change in kinetic energy

a. impulse

A rubber ball and a lump of putty have equal mass. They are thrown with equal speed against a wall. The ball bounces back with nearly the same speed with which it hit. The putty sticks to the wall. Which objects experiences the greater momentum change? a. the ball b. Both experience zero momentum change. c. the putty d. Both experience the same non-zero momentum change.

a. the ball

In an INELASTIC collision between two objects a. the momentum of the system is conserved but the kinetic energy of the system is not conserved. b. both the momentum and the kinetic energy of the system are conserved. c. the kinetic energy of each object is conserved. d. the momentum of each object is conserved.

a. the momentum of the system is conserved but the kinetic energy of the system is not conserved.

An object hits a wall and bounces back with half of its original speed. What is the ratio of the final kinetic energy to the initial kinetic energy? a. 1/2 b. 1/4 c. 4 d. 2

b. 1/4

A ping-pong ball moving east at a speed of 4 m/s, collides with a stationary bowling ball. The Ping-Pong ball bounces back to the west, and the bowling ball moves very slowly to the east. Which object experiences the greater magnitude impulse during the collision? a. It's impossible to tell since the velocities after the collision are unknown b. Neither; both experienced the same magnitude impulse. c. the bowling ball d. the Ping-Pong ball

b. Neither; both experienced the same magnitude impulse.

What is the quantity used to measure an object's resistance to changes in rotational motion? a. torque b. moment of inertia c. angular acceleration d. mass

b. moment of inertia

Rolling without slipping depends on a. kinetic friction between the rolling object and the ground. b. static friction between the rolling object and the ground. c. tension between the rolling object and the ground. d. normal force between the rolling object and the ground.

b. static friction between the rolling object and the ground.

Which of the following statements most accurately describes the center of gravity of an object? a. It is the point where gravity acts on the object. b. It is the point where all the mass is concentrated. c. It is the point from which the torque produced by the weight of the object can be calculated. d. It is the point on the object where all of the weight is concentrated.

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

A ball 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. Which one of the following statements provides an explanation for this increase? a. When the string is pulled downward, the angular momentum must increase. b. The total mechanical energy of the ball must remain constant because energy is conserved. c. The angular momentum of the ball is conserved in this process. d. This follows from applying Newton's 3rd law of motion.

c. The angular momentum of the ball is conserved in this process.

A child standing on the edge of a freely spinning merry-go-round moves quickly to the center. Which one of these statements is necessarily true if there is no friction involved and why? a. The angular speed of the system increases because the moment of inertia of the system has increased. b. The angular speed of the system remains the same because the net torque on the merry-go-round is zero Nm. c. The angular speed of the system increases because the moment of inertia of the system has decreased. d. The angular speed of the system decreases because the moment of inertia has decreased.

c. The angular speed of the system increases because the moment of inertia of the system has decreased.

A collision between two objects is elastic. Which one of the following statements concerning this situation is true? a. The vector sum of the velocities of the two objects is equal to zero m/s after the collision. b. The total momentum of the objects is zero kg*m/s after the collision. c. The total kinetic energy of the objects is the same before and after the collision. d. The objects stick together and move as one after the collision.

c. The total kinetic energy of the objects is the same before and after the collision.

A person sits on a freely spinning lab stool (no friction). When this person extends her arms, a. her moment of inertia decreases and her angular velocity increases. b. her moment of inertia decreases and her angular velocity decreases. c. her moment of inertia increases and her angular velocity decreases. d. her moment of inertia increases and her angular velocity increases.

c. her moment of inertia increases and her angular velocity decreases.

Two pucks on an air hockey table collide elastically. Complete the following statement: when such a collision occurs in two dimensions, the before and after velocities are best determined by a. making use of the work-energy theorem. b. using the fact that momentum is conserved and that the initial speeds of the objects must equal the final speeds of the objects. c. remembering the momentum is a vector quantity that is conserved in each direction. d. using the fact that total kinetic energy is conserved.

c. remembering the momentum is a vector quantity that is conserved in each direction.

A disk, a hoop, and a solid sphere are released at the same time at the top of an inclined plane. They all roll without slipping. In what order do they reach the bottom? a. disk, hoop, sphere b. hoop, disk, sphere c. sphere, disk, hoop d. hoop, sphere, disk

c. sphere, disk, hoop

Complete the following statement: For a wheel that turns with constant angular speed, a. each point on its rim moves with constant acceleration. b. the angular displacement of a point on the rim is constant. c. the wheel turns through "equal angles in equal times." d. each point on the rim moves at constant velocity.

c. the wheel turns through "equal angles in equal times."

Over the course of a day (twenty-four hours), what is the angular displacement of the minute hand of a wrist watch in radians? a. 9050 rad b. 1440 rad c. 2880 rad d. 151 rad

d. 151 rad

Which of the following is true for an object in equilibrium? a. The sum of the horizontal forces is zero. b. The sum of the torques is zero. c. The sum of the vertical forces is zero. d. All of these.

d. All of these.

Which of the following statements is true concerning momentum? a. Momentum is a scalar quantity. b. Momentum is a force. c. Momentum is a velocity. d. Momentum and impulse are measured in the same units.

d. Momentum and impulse are measured in the same units.

The momentum of an object is not dependent on which one of the following quantities? a. velocity b. mass c. inertia d. acceleration

d. acceleration

Complete the following statement: When determining the net torque on a rigid body, only the torques due to a. internal and external forces are considered. b. internal forces are considered. c. forces that form action-reaction pairs as in applying Newton's third law of motion are considered. d. external forces are considered.

d. external forces are considered.

Angular momentum cannot be conserved if a. the angular velocity changes. b. the moment of inertia changes. c. the angular acceleration changes. d. the net torque is not zero.

d. the net torque is not zero.

Complete the following statement: The center of mass is a. the region of an object where most of the mass is located. b. the only point on an object at which the gravitational force acts. c. the point at the geometrical center of an object. d. the point within an object that moves as if all of the object's mass were located there.

d. the point within an object that moves as if all of the object's mass were located there.