PHYS 201 : Momentum and Rotation (Exam 3)

A lighter and heavier box are at rest on a frictionless surface. The same force pushes on each box for 1 m. Which box has the larger change in kinetic energy after pushing?

same

A lighter and heavier box are at rest on a frictionless surface. The same force pushes on each box for 1 m. Which box has the larger change in momentum after pushing?

heavier

A lighter and heavier box are at rest on a frictionless surface. The same force pushes on each box for 1 second. Which box has the larger change in momentum after pushing?

same

A lighter and heavier box are at rest on a frictionless surface. The same force pushes on each box for 1 second. Which box has the larger change in kinetic energy after pushing?

lighter

Two boxes of different mass are at rest. If both boxes are acted upon equal force, what is true?

All of the above.

Right

Up

Out of the page

Out of the page

Up

Left

Out of the page

Q1 a

Down

Q1 b

Left

Counterclockwise

Moment of inertia decreases.

Cylinder

Angular velocity increases, kinetic energy increases.

Down

Down

Into the page

Out of the page

Q1 a

Down

Q1 b

Up

Q1 c

Down

Q1 d

Up

Q2

D

Q3

B

Q4

Ring

Q5

Same

Q6

Right

Q7

Up

Left

An elevator is moving upward at constant speed. Is the amount of net work being done to the elevator Positive, Negative, or Zero?

Zero

If there is net work done on an object, then

its travel direction may change and it always speeds up/slow down.

Starting from rest, a ball of mass 5 kg experiences a constant force of 8 N. What is the final kinetic energy (in J) of the ball after the force has been applied for a distance of 4m?

32 J

A 12 kg block is moving 4 m/s to the right on a frictionless surface. A Force of 24 N to the right is applied to the block for 5 seconds. As a result of this force, the final momentum of the block is:

168 kg m/s

A Force of 50 N is used to move a box. Which of the following statements is true about the Work and the Impulse due to this Force:

The Impulse depends on the time, and the Work depends on the distance the box was pushed.

An astronaut with a mass of 80kg is floating in space. If the astronaut throws a space rock with a mass of 4 kg at a speed of 40 m/s, what will be the resultant recoil speed of the Astronaut?

2 m/s

A student is seated on a barstool with two heavy weights in her extended arms. She is rotating counterclockwise at a speed of omega. She slowly brings her arms closers to her body. Based on this information which statement is true?

The angular velocity increases.

Box A

-11 rad/s

Intro the screen

What direction is the angular momentum?

Up

What direction is the angular momentum?

Right

What direction is the torque (Force is out of the page and applied at the top of the wheel)?

Right

What direction is the angular momentum?

Down

What direction is the torque (Force is to the right, applied at the bottom of the wheel)?

Out of the page

If a net force is exerted on an object for a given amount of time, then momentum _____ changes and kinetic energy _____ change.

always; may

True or false: Momentum is a vector.

True

When two objects interact, the change in momentum of one exactly _____ the change in momentum of the other.

cancels

An _____ collision occurs when kinetic energy is conserved.

elastic

An _____ collision occurs when kinetic energy is NOT conserved.

inelastic

A _______ _______ collision occurs when both objects stick together and have the same final velocity.

perfectly inelastic

Calculate the magnitude of the recoil velocity of a 11.5 kg rifle that fires a 0.0500 kg bullet with a muzzle velocity of 600 m/s. If the rifle pushes against the man's shoulder for 1.67 s after it is fired, find the magnitude of the average force (in N) exerted as the gun recoils.

-2.61 m/s ; 18 N