Chapter 7 Physics

Interactive QuestionSuppose a ping-pong ball and a bowling ball are rolling toward you. Both have the same momentum, and you exert the same force to stop each. How do the time intervals to stop them compare?A) It takes less time to stop the ping-pong ball. B) Both take the same time.C) It takes more time to stop the ping-pong ball.

A) It takes less time to stop the ping-pong ball. (impulse) formula

These two skaters start from rest push off against one another. One skater has more mass as the other. Which of the following is true after the push off?A) The skaters have the same momenta but different velocities.B) The skaters have the same momenta and the same velocities.C) The skaters have different momentum and different velocities.D) The skaters have different momentum but the same velocities.

A) The skaters have the same momenta but different velocities.

A rubber ball and a lump of putty have equal mass. They are thrown with equal speed against a wall. The ball bounces back with nearly the same speed with which it hit. The putty sticks to the wall. Which object experiences the greater momentum change?

A. ) The ball

A compact car and a large truck collide head on and stick together. Which undergoes the larger acceleration during the collision?

A.) The car

Two forces produce equal impulses, but the second force, F2, acts for a time twice that of the first force, F1. Which of the following is true?A) F1= F2 B) F1= 2F2C) F1= 4F2 D) 2F1= F2E) 4F1= F2

B) F1= 2F2

You are on a cart initially at rest on a track with no friction. You throw balls at a partition that is rigidly mounted on the cart. If the balls bounce straight back as shown, is the cart put in motion?

B.) yes, it moves to the left

You are on a cart initially at rest on a track with no friction. You throw balls off the cart to the right. Is the cart put in motion?

B.) yes, it moves to the left

A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the magnitude of the collision force is correct? A) The truck experiences the greater average force. B) The small car experiences the greater average force. C) The small car and the truck experience the same average force. D) It is impossible to tell since the masses and velocities are not given.

C) The small car and the truck experience the same average force

How do seat belts and air bags save lives?A) They add backward momentum to your forward momentum to give less total momentum.B) They change your final momentum compared to not having them.C) They increase the time of impact which means there is less force and less acceleration on you.D) They change the amount of kinetic energy the car has.

C) They increase the time of impact which means there is less force and less acceleration on you.

A compact car and a large truck collide head on and stick together. Which undergoes the larger momentum change?

C) the momentum change is the same for both

The total momentum of an isolated system of objects remains ______.

Constant

An unfortunate duck flying through the air is hit by an airplane. Which of the following quantities is NOT the same for the duck and the airplane?A) The time of collisionB) The magnitude of the force felt by eachC) The magnitude of the change in momentum D) The magnitude of the change in velocityE) None of the above

D) The magnitude of the change in velocity (p=mv) the momentum is conserved velocity change bc they have different masses

Which of the following is true? A) The momentum of a tennis ball can never be equal to the momentum of a car. B) The momentum of a tennis ball will always be equal to the momentum of a car. C) The momentum of a tennis ball can be equal to the momentum of a car only if neither of them are moving. D) The momentum of a tennis ball can be equal to the momentum of a car if they are moving the same speed. E) The momentum of a tennis ball can be equal to the momentum of a car if the tennis ball is moving much faster than the car or if neither of them are moving.

E) The momentum of a tennis ball can be equal to the momentum of a car if the tennis ball is moving much faster than the car or if neither of them are moving.

If on the _____ changes, then the momentum still changes

direction

When two objects collide with one another external forces, the change in momentum of one object is____ and ______ to the change in momentum of the other object.

equal, opposite

large momentum is achieved by having a ___mass, or a ___ speed, or both

large, large

Momentum formula

p = mv

Newton's second Law: The rate of change of momentum of an object is ______ to the net force applied to it

proportional

The conversation of linear momentum:

this means that in any process, the total momentum after the process is the same as the total momentum before the process.

As far as we know always set the impulse to equal _____?

zero