question

A Mack truck and a small Volkswagen collide head on. Which of the following statements is true about the collision?

answer

The force the Volkswagen exerts on the truck is equal to the force the truck exerts on the Volkswagen.

question

A truck rear-ends a car that is initially stationary. The truck weighs ten times more than the car. Which statement is true about the collision?

answer

The magnitude of the acceleration of the car is ten times greater than the magnitude of the acceleration of the truck.

question

A glass that falls onto a carpeted floor has less chance of breaking than a glass that falls (from the same height) onto a wooden floor. Why?

answer

The glass that falls onto the carpet takes a longer time to stop.

question

A stationary 100-kg person is initially holding a 50-kg ball while standing on a skateboard. The person throws the ball to the right, and the ball moves (with respect to the ground) with a speed of 12 m/s. The person on the skateboard ____________.

answer

moves to the left with a speed of 6 m/s

question

Consider two carts, initially at rest. Cart 1 is twice as massive as cart 2. If you push on cart 1 for 3 seconds and then push on cart 2 with the same force for 3 seconds, how do the final momenta of the two carts compare? (Ignore the effect of friction.)

answer

The momenta of the two carts are equal.

question

Consider two carts, initially at rest. Cart 1 is twice as massive as cart 2. If you push on cart 1 for 3 seconds and then push on cart 2 with the same force for 3 seconds, how do the final speeds of the two carts compare? (Ignore the effect of friction.)

answer

The speed of cart 2 is twice as great as that of cart 1.

question

A 200-lb person pushes on the back of a 100-lb person. Both people are on skateboards and are initially stationary. After the push, the 200-lb person is moving to the right with a speed of 4 m/s. The 100-lb person is ________.

answer

moving to the left with a speed of 8 m/s

question

A car is driving down the highway with an initial speed of 30 m/s. It slams into the back of an identical car (same mass), which was initially going only 10 m/s (in the same direction as the faster car). If the collision is perfectly inelastic, the final speed of the two cars is ________.

answer

20 m/s

question

A slowly moving ship can have a greater momentum than a fast-moving racing car when _______.

answer

its mass times velocity is greater than that of the car.

question

The quantity that is called impulse can be measured by the _______.

answer

product of force and time.

question

An impulse can be increased by

answer

increasing the force or increasing the time interval.

question

A boxer rides with the punch so as to reduce _______.

answer

force

question

Follow through is important in golf because it results in a greater _______

answer

impulse on the ball.

question

Distinguish between force and impulse.

answer

Impulse is force times a time interval.

question

Which has a greater momentum: a heavy truck at rest or a moving skateboard?

answer

The moving skateboard.

question

How is the impulse -momentum relationship related to Newton's second law?

answer

F=ma=mΞv/Ξt, so Ft=Ξ(mv)

question

Why is a force that is applied for a short time more effective in karate?

answer

The average force is increased.

question

Why is it advantageous to roll with the punch in boxing?

answer

Rolling with the punch increases contact time, which decreases the force.

question

What is the momentum of an 8.6-kg bowling ball rolling at 2.2 m/s ?

answer

19 kgm/s

question

What is the momentum of a 44-kg carton that slides at 3.4 m/s across an icy surface?

answer

150 kgm/s

question

What impulse occurs when the force of 14 N acts on the cart for the time 5.4 s ?

answer

76 kgm/s

question

What is the magnitude of the impulse on an 7.2-kg ball rolling at 2.8 m/s when it bumps into a pillow and stops?

answer

20 NxS

question

How much impulse stops a 40-kg carton sliding at 4.8 m/s when it meets a rough surface?

answer

190 NxS

question

What impulse occurs when an average force of 12 N is exerted on a cart for 2.9 s ?

answer

35 kgm/s

question

Cassy can get more force on the bricks she breaks with a blow of her bare hand when _______.

answer

her hand is made to bounce from the bricks.

question

When a cannonball is fired from a cannon, the momentum of the recoiling cannon is momentarily _______.

answer

equal and opposite to the momentum of the fired cannonball.

question

When two vehicles collide, momentum is conserved _______.

answer

whether the collision is elastic or inelastic.

question

When a big fish swims into an oncoming smaller fish and swallows it, the momentum of the two-fish system _______.

answer

remains the same.

question

what will happen if the red and green truck with equal mass and equal magnitude of velocity collide?

answer

The trucks will stick together after the collision and not move.

question

what will happen if you reduce the magnitude of the velocity of the green truck to a magnitude smaller than that of the red truck?

answer

The trucks will stick together after the collision and move to the left.

question

How much of the balls' kinetic energy is dissipated?

answer

None of it

question

When a cue ball strikes an 8 ball head-on in a game of pool, the cue ball _______.

answer

transfers its momentum to the 8 ball.

question

What does it mean to say that momentum is conserved?

answer

It means momentum does not change.

question

When a falling firecracker explodes, the momenta of its pieces _______.

answer

vectorally add up to equal the initial momentum of the firecracker

question

Railroad car A rolls at a certain speed and makes a perfectly elastic collision with car B of the same mass. After the collision, car A is observed to be at rest. How does the speed of car B compare with the initial speed of car A?

answer

The speed of car B is equal to the initial speed of A.