Question 1

A 2 kg ball is moving at 3 m/s. What is its momentum?

Accepted Answer

$$6\ \mathrm{kg\cdot m/s}$$

Question 2

If the velocity of an object is doubled, what happens to its momentum?

Accepted Answer

It doubles.

Question 3

A car of mass $$m$$ moving at velocity $$v$$ comes to a stop after hitting a haystack, taking time $$t to $$stop. What is the impulse delivered to the car?

Accepted Answer

$$mv$$

Question 4

A baseball player follows through when hitting a ball. Why does this increase the ball's change in momentum?

Accepted Answer

It increases the time the force acts, increasing the impulse.

Question 5

A moving car hits a cement wall and comes to a stop in 0.1 s. If the same car hits a haystack and stops in 1 s, which scenario involves a greater force?

Accepted Answer

Hitting the cement wall.

Question 6

Which of the following best describes the law of conservation of momentum?

Accepted Answer

In the absence of external forces, the total momentum of a system remains constant.

Question 7

Two ice skaters push off from one another. If one skater is twice as massive as the other, how do their momenta compare after they push off?

Accepted Answer

Both have equal and opposite momenta.

Question 8

A karate expert breaks a stack of bricks with a swift blow. Why is the force of impact so large?

Accepted Answer

Because the time of contact is very short.

Question 9

A 1000 kg car moving at 10 m/s collides with a 1000 kg car at rest. If they stick together after the collision, what is their final speed?

Accepted Answer

$$5\ \mathrm{m/s}$$

Question 10

Which of the following is true for an elastic collision?

Accepted Answer

The objects rebound without lasting deformation or heat generation.

Question 11

A firecracker explodes at rest. What is the vector sum of the momenta of all its pieces after the explosion?

Accepted Answer

Zero.

Question 12

A flowerpot falls and is caught by a person who then throws it upward. Compared to just catching it, what is the total impulse provided?

Accepted Answer

Greater, because the impulse to stop and then reverse the motion is larger.

Question 13

A dish falls and lands on a carpet instead of a hard floor. Why is it less likely to break?

Accepted Answer

The force is less because the stopping time is longer.

Question 14

Which of the following scenarios best illustrates the concept of impulse?

Accepted Answer

A person pushing a stalled car for 5 seconds.

Question 15

A cannon fires a cannonball. What happens to the momentum of the cannon and the cannonball?

Accepted Answer

The cannonball gains momentum, and the cannon gains equal momentum in the opposite direction.

Question 16

Which of the following is NOT a characteristic of an inelastic collision?

Accepted Answer

Kinetic energy is conserved.

Question 17

A soccer player kicks a ball with a force of $$50\ \mathrm{N}$$ for $$0.2\ \mathrm{s}. $$What is the impulse delivered to the ball?

Accepted Answer

$$10\ \mathrm{N\cdot s}$$

Question 18

In a two-dimensional collision, how is the total momentum of the system found?

Accepted Answer

By constructing a vector sum (parallelogram) of the individual momenta.

Question 19

A boxer 'rides' with a punch to reduce the force of impact. This is because:

Accepted Answer

It increases the time over which the force acts, reducing the force.

Question 20

Which of the following best explains why a Pelton wheel is designed to make water 'bounce' off its paddles?

Accepted Answer

To maximize the impulse and thus the change in momentum transferred to the wheel.

Chapter 6: Momentum – Study Notes for College Physics

Study Guide - Practice Questions

Study Guide - Flashcards