Question 1

A soccer player kicks a stationary ball, and the force applied by the foot rises quickly to a maximum and then falls back to zero over a short time. Which of the following best describes the impulse delivered to the ball?

Accepted Answer

The impulse is the area under the force-versus-time curve during contact.

Question 2

A 0.25 kg ball moving at $$1.3\ \mathrm{m/s} to $$the right strikes a wall and rebounds to the left at $$1.1\ \mathrm{m/s}. $$What is the change in the ball’s momentum?

Accepted Answer

$$0.60\ \mathrm{kg\cdot m/s} to $$the left

Question 3

A 1.0 kg cue ball is struck by two different cues. Cue 1 applies a force of $$100\ \mathrm{N}$$ for $$2\ \mathrm{ms}$$, and Cue 2 applies $$10\ \mathrm{N}$$ for $$20\ \mathrm{ms}. $$Which ball has the greater final speed?

Accepted Answer

Both balls have the same final speed.

Question 4

A 2.0 kg object moving to the right at $$0.50\ \mathrm{m/s}$$ experiences a force that brings it to rest. What is the impulse delivered by the force?

Accepted Answer

$$-1.0\ \mathrm{kg\cdot m/s}$$

Question 5

A karate expert delivers a blow to a $$1\ \mathrm{kg}$$ board, moving her hand at $$10\ \mathrm{m/s}$$ and stopping it in $$0.002\ \mathrm{s}. $$What is the average force exerted on the board?

Accepted Answer

$$5000\ \mathrm{N}$$

Question 6

A 0.060 kg tennis ball leaves a racket at $$55\ \mathrm{m/s}$$ after being in contact for $$4\$$times10^{-3}$$\ \mathrm{s}. $$What is the average force exerted by the racket?

Accepted Answer

$$825\ \mathrm{N}$$

Question 7

A car traveling at $$20\ \mathrm{m/s}$$ crashes into a barrier. If the driver is stopped by a $$1\ \mathrm{m}$$ crumple zone, which of the following will decrease the force on the driver?

Accepted Answer

Increasing the duration of the collision

Question 8

A 1-kg box slides on a frictionless surface and collides with a 2-kg box. They stick together after the collision. If the 1-kg box was moving at $$3\ \mathrm{m/s}$$ and the 2-kg box was at rest, what is their final speed?

Accepted Answer

$$1\ \mathrm{m/s}$$

Question 9

Two ice skaters, Sandra ($$45\ \mathrm{kg}) $$and David ($$80\ \mathrm{kg}$$), push off from each other on frictionless ice. Sandra moves at $$2.2\ \mathrm{m/s} to $$the right. What is David’s speed and direction?

Accepted Answer

$$1.2\ \mathrm{m/s} to $$the left

Question 10

A 30 g ball is fired from a $$1.2\ \mathrm{kg}$$ toy rifle at $$15\ \mathrm{m/s}. $$What is the recoil speed of the rifle?

Accepted Answer

$$0.38\ \mathrm{m/s}$$

Question 11

A peregrine falcon ($$0.80\ \mathrm{kg}) $$dives at $$18\ \mathrm{m/s} at a$$ $$45^\circ$$ angle and grabs a $$0.36\ \mathrm{kg}$$ pigeon flying horizontally at $$9.0\ \mathrm{m/s}. $$What is the speed of the combined birds immediately after the collision?

Accepted Answer

$$15\ \mathrm{m/s}$$

Question 12

Which of the following statements about momentum is correct?

Accepted Answer

Momentum is a vector quantity and points in the same direction as velocity.

Question 13

A light plastic cart and a heavy steel cart are both pushed with the same force for $$1.0\ \mathrm{s}$$, starting from rest. After the force is removed, the momentum of the light plastic cart is:

Accepted Answer

Equal to that of the heavy steel cart

Question 14

A 10 g bullet is fired into a $$1.0\ \mathrm{kg}$$ wood block and lodges inside. The block slides $$4.0\ \mathrm{m}$$ across the floor before stopping. Which principle is most useful for finding the bullet’s initial speed?

Accepted Answer

Conservation of momentum

Question 15

A merry-go-round (modeled as a disk) rotates with a child standing at the center. As the child walks to the edge, what happens to the angular velocity and why?

Accepted Answer

Angular velocity decreases because the moment of inertia increases.

Question 16

Which of the following is true for a perfectly inelastic collision?

Accepted Answer

The objects stick together and move with a common final velocity.

Question 17

A mosquito and a truck have a head-on collision. Which has the larger change in momentum?

Accepted Answer

Both have the same magnitude of change in momentum.

Question 18

A system is considered isolated if:

Accepted Answer

The net external force acting on it is zero.

Momentum, Impulse, and Conservation Laws: Physics with Calculus Study Guide

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