PHY Chapter 6

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 A) 0.5 m/s. B) 0.33 m/s. C) 0.67 m/s. D) 1.0 m/s. E) none of the above

A) 0.5 m/s.

The speed of a 4-kg ball with a momentum of 12 kg m/s is A) 3 m/s. B) 4 m/s. C) 12 m/s. D) 48 m/s. E) none of the above

A) 3 m/s.

When Freddy Frog drops vertically from a tree onto a horizontally-moving skateboard, the speed of the skateboard A) decreases. B) increases. C) neither decreases nor increases.

A) decreases.

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 A) greater. B) smaller. C) the same.

A) greater

Padded dashboards in cars are safer in an accident than non-padded ones because passengers hitting the dashboard encounter A) lengthened time of contact. B) shorter time of contact. C) decreased impulse. D) increased momentum.

A) lengthened time of contact.

Two billiard balls having the same mass and speed roll toward each other. What is their combined momentum after they meet? A) zero B) half the sum of their original momentums C) twice the sum of their original momentums D) need more information

A) zero

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 A) 0 kg m/s. B) 1 kg m/s. C) 2 kg m/s. D) 5 kg m/s. E) more than 5 kg m/s.

B) 1 kg m/s.

The average braking force of a 1000-kg car moving at 10 m/s braking to a stop in 5 s is A) 1000 N. B) 2000 N. C) 3000 N. D) 4000 N. E) 5000 N

B) 2000 N.

It is correct to say that impulse is equal to A) momentum. B) a corresponding change in momentum. C) force multiplied by the distance it acts. D) velocity multiplied by time.

B) a corresponding change in momentum.

Which of the following has the largest momentum relative to Earth's surface? A) a tightrope walker crossing Niagara Falls B) a pickup truck speeding along a highway C) a Mack truck parked in a parking lot D) the Science building on campus E) a mouse running across your room

B) a pickup truck speeding along a highway

A karate chop is more effective if one's hand A) follows through upon impact. B) bounces upon impact. C) extends the time upon impact

B) bounces upon impact.

Whether a truck comes to a stop by crashing into a haystack or a brick wall, the stopping force is A) greater with the haystack. B) greater with the brick wall. C) both the same

B) greater with the brick wall.

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 A) zero. B) twice. C) four times as much. D) unchanged.

B) twice.

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 A) less than 1 unit. B) more than 1 unit. C) 1 unit. D) need more information

C) 1 unit.

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 A) 1/2 m/s. B) 1/5 m/s. C) 1/6 m/s. D) 2/3 m/s. E) 3/2 m/s.

C) 1/6 m/s

The mass of a ball moving at 3 m/s with a momentum of 48 kg m/s is A) 4 kg. B) 12 kg. C) 16 kg. D) 144 kg. E) none of these

C) 16 kg

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 A) 1,000 kg m/s. B) 2,000 kg m/s. C) 3,000 kg m/s. D) 4,000 kg m/s. E) 9,000 kg m/.

C) 3,000 kg m/s.

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 A) 1/2 m/s. B) 2/5 m/s. C) 5/6 m/s. D) 6/5 m/s. E) 1 m

C) 5/6 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 A) 2 kg m/s. B) 4 kg m/s. C) 6 kg m/s. D) 8 kg m/s.

C) 6 kg m/s.

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? A) 4 m/s B) 5 m/s C) 6 m/s D) 8 m/s E) none of the above

C) 6 m/s

Whether a truck comes to a stop by crashing into a haystack or a brick wall, the impulse is A) greater with the haystack. B) greater with the brick wall. C) both the same

C) both 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? A) car B) wall C) both the same D) need more information

C) both the same

A cannon recoils while firing a cannonball. The speed of the cannon's recoil is relatively small because the A) force against the cannon is smaller than against the ball. B) momentum is mainly concentrated in the cannonball. C) cannon has much more mass than the cannonball. D) momentum of the cannon is smaller.

C) cannon has much more mass than the cannonball.

Which has the greater momentum when moving? A) a container ship B) a bullet C) either of these depending on speed

C) either of these depending on speed

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 A) speed. B) acceleration. C) momentum. D) all of the above E) none of the above

C) momentum.

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 A) force of contact is reduced. B) relative velocity is less. C) time of contact is increased. D) time of contact is decreased. E) none of the above

C) time of contact is increased.

A car traveling along the highway brakes to a stop over a certain distance. More braking force is required if the car has A) more mass. B) more momentum. C) less stopping distance. D) all of the above E) none of the above

D) all of the above

When Peter tosses an egg against a sagging sheet, the egg doesn't break due to A) reduced impulse. B) reduced momentum. C) both of these D) neither of these

D) neither of these