Ch6 Practice Test

A 5000-kg freight car collides with a 10,000 -kg freight car at rest. They couple upon collision and move at 2 m/s. What was the initial speed of the 5000 -kg car?

6 m/s

The change in momentum that occurs when a 1.0 kg ball traveling at 4.0 m/s strikes a wall and bounces back at 2.0 m/s is...

6kg m/s

When Peter tosses an egg against a sagging sheet, the egg doesn't break due to...

neither reduced impulse nor reduced momentum

The conservation of momentum is most closely related to...

newtons 3rd law

When a boxer moves into an oncoming punch, the force experienced is...

increased

Padded dashboards in cars are safer in an accident than non-padded ones because passengers hitting the dashboard encounter...

lengthened time of contact

A red car has a head-on collision with an approaching blue car with the same magnitude of momentum. A green car driving with the same momentum as the other cars collides with an enormously massive wall. Which of the three cars will experience the greatest impulse?

they are all the same

Which produces more force: driving into a very massive concrete wall with no "give," or having a head-on collision with an identical car moving toward you at the same speed?

they are both the same

To catch a fast-moving ball, you extend your hand forward before contact with the ball and let it ride backward in the direction of the ball's motion. Doing this reduces the force of contact on your hand principally because the....

time of contact is increased

The mass of a ball moving at 3 m/s with a momentum of 48 kg m/s is...

16kg

The mass of a ball moving at 3m/s with a momentum of 48 kg m/s is...

16kg

A 2-kg rifle that is suspended by strings fires a 0.01-kg bullet at 200 m/s. The recoil velocity of the rifle is about...

1 m/s

A piece of putty moving with 1 unit of momentum strikes and sticks to a heavy bowling ball that is initially at rest. Both move with a combined momentum of...

1 unit

Two identical objects in outer space, one moving at 2 m/s, the other at 1 m/s, have a head-on collision and stick together. Their combined speed after the collision is...

0.5m/s

A 1-kg glider and a 2-kg glider both slide toward each other at 1 m/s on an air track. They collide and stick. The combined mass moves at...

1/3 m/s

A 5-kg shark swimming at 1 m/s swallows an absent-minded 1-kg fish swimming toward it at 4 m/s. The speed of the shark after his meal is...

1/6 m/s

A 1-kg chunk of putty moving at 1 m/s collides with and sticks to a 5-kg bowling ball initially at rest. The bowling ball and putty then move with a momentum of...

1kg m/s

The average braking force of a 1000 -kg car moving at 10 m/s braking to a stop in 5 s is...

2000N

The speed of a 4-kg ball with a momentum of 12 kg m/s is...

3 m/s

The speed of a 4kg ball with a momentum of 12kg m/s is...

3 m/s

A motorcycle of mass 100 kilograms slowly rolls off the edge of a cliff and falls for three seconds before reaching the bottom of a gully. Its momentum upon hitting the ground is...

3000 kg m/s

A 5-kg fish swimming at 1 m/s swallows an absent-minded 1-kg fish at rest. The speed of the larger fish after lunch is...

5/6 m/s

It is correct to say that impulse is equal to...

a corresponding change in momentum

Which of the following has the largest momentum relative to Earth's surface?

a pickup truck speeding along a highway

If several balls are thrown straight up with different initial speeds, the quantity that will have the same value along their paths is their...

acceleration

Whether a truck comes to a stop by crashing into a haystack or a brick wall, the impulse is...

both the same

A karate chop is more effective if one's hand...

bounces upon impact

A cannon recoils while firing a cannonball. The speed of the cannon's recoil is relatively small because the...

cannon has much more mass than the cannonball

When bullets are fired from an airplane in the forward direction, the momentum of the airplane is...

decreased

When Freddy Frog drops vertically from a tree onto a horizontally-moving skateboard, the speed of the skateboard...

decreases

Which has the greater momentum when moving?

either a container ship or a bullet, depending on speed

The total momentum of a flock of identical birds could be zero only if the birds are...

flying in different directions

A heavy truck and a small car rolling down a hill at the same speed are forced to stop in the same amount of time. Compared with the force that stops the car, the force needed to stop the truck is...

greater

Whether a truck comes to a stop by crashing into a haystack or a brick wall, the stopping force is...

greater with the brick wall

A softer landing occurs when a falling object bounces from a surface...

in a extended time

A same-size iron ball and wooden ball are dropped simultaneously from a tower and reach the ground at the same time. The iron ball has a greater...

momentum

A car traveling along the highway brakes to a stop over a certain distance. More braking force is required if the car has...

more mass, more momentum and less stopping distance

A golf ball moving forward with 1 unit of momentum strikes and bounces backward off a heavy bowling ball that is initially at rest and free to move. The bowling ball is set in motion with a momentum of...

more than 1 unit

A freight train rolls along a track with considerable momentum. If it rolls at the same speed but has twice as much mass, its momentum is...

twice

Two billiard balls having the same mass and speed roll toward each other. What is their combined momentum after they meet?

zero