Q: Which of the following best describes the impulse-momentum theorem?

$$J = \Delta p = F_{\text{net}} \Delta t$$

Q: A 1.00 kg block moves to the right at 6.00 m/s on a frictionless surface. A 3.00 kg block is at rest. What is the velocity of the center of mass of the system before collision?

$$v_{\text{cm}} = 1.50\ \mathrm{m/s}$$\ to\ the\ right

Question 1

A 0.40 kg ball is moving to the left at 30 m/s. After hitting a wall, it rebounds to the right at 20 m/s. What is the impulse delivered to the ball by the wall?

Accepted Answer

$$J = 20\ \mathrm{kg\cdot m/s}$$\ to\ the\ right

Question 2

Which of the following best describes the impulse-momentum theorem?

Accepted Answer

$$J = \Delta p = F_{	ext{net}} \Delta t$$

Question 3

A soccer ball of mass 0.40 kg is initially moving to the left at 20 m/s. After being kicked, it moves at 30 m/s at a $$45^\circ$$ angle upward and to the right. What is the magnitude of the impulse delivered to the ball?

Accepted Answer

$$J = 16.97\ \mathrm{kg\cdot m/s}$$

Question 4

Two cars, each of mass $$m$$, collide head-on and stick together. If the first car was moving at $$v$$ and the second at $$-v$$, what is the velocity of the combined mass after the collision?

Accepted Answer

$$v_{	ext{final}} = 0$$

Question 5

In a crash test, a car is brought to a stop either by slamming into a wall or by plowing into a giant tub of gelatin. In which case is the impulse of the net force on the car greater?

Accepted Answer

The impulse is the same in both cases.

Question 6

A 1.00 kg block moves to the right at 6.00 m/s on a frictionless surface. A 3.00 kg block is at rest. What is the velocity of the center of mass of the system before collision?

Accepted Answer

$$v_{	ext{cm}} = 1.50\ \mathrm{m/s}$$\ to\ the\ right

Question 7

Which of the following is true for a completely inelastic collision between two objects with different masses and no external forces?

Accepted Answer

The system has the same total momentum but less total kinetic energy after the collision.

Question 8

A 2.0 kg glider moving at 2.0 m/s collides with a 0.5 kg glider at rest on a frictionless track. If the collision is perfectly elastic, what is the final velocity of the 0.5 kg glider?

Accepted Answer

$$v_{f} = 3.2\ \mathrm{m/s}$$

Question 9

Which statement about momentum is correct?

Accepted Answer

Momentum is a vector quantity and is conserved in isolated systems.

Question 10

A shell explodes in midair, breaking into two fragments. What happens to the center of mass of the system?

Accepted Answer

It continues to follow the original trajectory as if the shell had not exploded.

Question 11

A package lands in a cart rolling horizontally. Which quantity is conserved just before and just after the package lands?

Accepted Answer

The horizontal component of total momentum

Question 12

In a one-dimensional elastic collision between two bodies A and B, where B is initially at rest, which equation gives the final velocity of B?

Accepted Answer

$$v_{B,f} = \frac{2m_A}{m_A + m_B} v_{A,i}$$

Question 13

A rocket expels fuel and accelerates in space. Which principle best explains the rocket's motion?

Accepted Answer

Conservation of momentum

Question 14

Two astronauts, one of mass 90 kg and the other 60 kg, are 20 m apart on ice. If the 90 kg astronaut moves 6 m toward a mug placed midway, how far does the 60 kg astronaut move and in which direction?

Accepted Answer

Moves 9 m toward the mug

Question 15

Which of the following is true for an elastic collision?

Accepted Answer

Total kinetic energy is conserved.

Question 16

A 0.500 kg puck moving at 4.00 m/s collides elastically with a 0.300 kg puck at rest. If the final velocity of the 0.500 kg puck is 2.00 m/s at an angle, what is the final speed of the 0.300 kg puck?

Accepted Answer

$$v_{B,f} = 2.67\ \mathrm{m/s}$$

Question 17

Which of the following is the correct formula for the position of the center of mass of a system of particles?

Accepted Answer

$$\vec{r}_{	ext{cm}} = \frac{\sum m_i \vec{r}_i}{\sum m_i}$$

Question 18

A moving object A with mass $$m$$ collides elastically in 1D with a stationary object B of equal mass. What happens after the collision?

Accepted Answer

A stops and B moves with A's original velocity.

Momentum, Impulse, and Collisions – Study Notes

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드