Q: A 3 kg object moves east at 4 m/s. What is its momentum?

$$12\ \text{kg}\cdot\text{m/s}$$\ \text{east}$

Q: A bat hits a baseball, applying a force of 50 N for 0.02 s. What is the change in momentum of the ball?

$$1\ \text{kg}\cdot\text{m/s}$$

Q: A 2 kg object moving at 3 m/s receives an impulse of $$6\ \text{N}\cdot\text{s}. $$What is its final velocity?

$$(2\times3 + 6)\div2 = 6\ \text{m/s}$$

Q: A 1 kg ball moving at 4 m/s bounces off a wall and moves at -4 m/s. What is the impulse delivered by the wall?

$$J = m\cdot\Delta v = 1\times(-4-4) = -8\ \text{N}\cdot\text{s}$$

Question 1

A 3 kg object moves east at 4 m/s. What is its momentum?

Accepted Answer

$$12\ 	ext{kg}\cdot	ext{m/s}$$\ 	ext{east}$

Question 2

Which of the following best describes why momentum is a vector quantity?

Accepted Answer

Momentum depends on both the magnitude and direction of velocity.

Question 3

A 2 kg ball moving at 5 m/s collides with a stationary 3 kg ball. If the collision is perfectly elastic and the 2 kg ball comes to rest after the collision, what is the velocity of the 3 kg ball immediately after?

Accepted Answer

$$3.33\ 	ext{m/s}$$

Question 4

A 10 kg object moving at 2 m/s and a 5 kg object moving at 4 m/s have the same momentum. Which equation shows this relationship?

Accepted Answer

$$10	imes2 = 5	imes4$$

Question 5

A 1 kg cart moving at 3 m/s collides with a stationary 2 kg cart. After the collision, the 1 kg cart stops and the 2 kg cart moves. What is the velocity of the 2 kg cart, assuming momentum is conserved?

Accepted Answer

$$1.5\ 	ext{m/s}$$

Question 6

Which scenario best illustrates an inelastic collision?

Accepted Answer

A car crashes into a wall and crumples, sticking to the wall.

Question 7

A 10 N force acts on a ball for 0.5 s. What is the impulse delivered to the ball?

Accepted Answer

$$5\ 	ext{N}\cdot	ext{s}$$

Question 8

Why is landing on a foam pit safer than landing on concrete, in terms of impulse?

Accepted Answer

The foam pit increases the contact time $$\Delta t$$, reducing the force for the same impulse.

Question 9

A bat hits a baseball, applying a force of 50 N for 0.02 s. What is the change in momentum of the ball?

Accepted Answer

$$1\ 	ext{kg}\cdot	ext{m/s}$$

Question 10

Which equation correctly relates impulse to change in momentum?

Accepted Answer

$$J = m\cdot\Delta v$$

Question 11

A 500 kg cart moving at 2 m/s collides with a stationary 1000 kg cart and comes to rest. What is the velocity of the 1000 kg cart after the collision, assuming momentum is conserved?

Accepted Answer

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

Question 12

Which of the following statements about elastic collisions is correct?

Accepted Answer

Kinetic energy is conserved and objects bounce off each other.

Question 13

A 2 kg object moving at 3 m/s receives an impulse of $$6\ 	ext{N}\cdot	ext{s}. $$What is its final velocity?

Accepted Answer

$$(2	imes3 + 6)\div2 = 6\ 	ext{m/s}$$

Question 14

During a collision, why does increasing the contact time $$\Delta t$$ reduce the force experienced?

Accepted Answer

Because $$F = \frac{m\cdot\Delta v}{\Delta t}$$, so a larger $$\Delta t$$ means a smaller $$F$$ for the same change in momentum.

Question 15

A 5 kg object at 2 m/s and a 10 kg object at 1 m/s have the same momentum. If both objects collide and stick together, what is their final velocity?

Accepted Answer

$$1.33\ 	ext{m/s}$$

Question 16

Which of the following best explains how airbags protect drivers in a crash?

Accepted Answer

Airbags increase the contact time $$\Delta t$$, reducing the force for the same impulse.

Question 17

A 1 kg ball moving at 4 m/s bounces off a wall and moves at -4 m/s. What is the impulse delivered by the wall?

Accepted Answer

$$J = m\cdot\Delta v = 1	imes(-4-4) = -8\ 	ext{N}\cdot	ext{s}$$

Question 18

In a collision between two objects, which condition must be met for momentum to be conserved?

Accepted Answer

The system must be isolated with no external forces.

Question 19

A 2 kg object moving at 3 m/s collides with a 3 kg object moving at -2 m/s. What is the total momentum before the collision?

Accepted Answer

$$(2	imes3) + (3	imes-2) = 6 - 6 = 0\ 	ext{kg}\cdot	ext{m/s}$$

Momentum and Impulse: Study Guide for Physics 100 (Chapter 6)

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