physic ch6

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

.5 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

1 kg m/s.

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.

A bungee jumper attains a speed of 30 m/s just as the bungee cord begins to stretch. If the period of stretch is 2 s while coming to a halt, the jumper's average deceleration is about

1.5 g

Two identical gliders slide toward each other on an air track. One moves at 1 m/s and the other at 2 m/s. They collide, stick, and moves at

1/2 m/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

Consider massive gliders that slide friction-free along a horizontal air track. Glider A has a mass of 1 kg, a speed of 1 m/s, and collides with Glider B that has a mass of 5 kg and is at rest. If they stick upon collision, their speed after collision will be

1/6 m/s

If you can't avoid being hit by a fast-moving object, you'll suffer a smaller contact force if you can extend that force over a

a longer time

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

a pick up truck speeding a long a highway

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

either of these depending on speed

A firecracker bursts while freely falling. The combined momentum of its fragments cancels to the firecracker's momentum at the time of bursting.

equals the momentum of the firecracker at the time of burst

The force that accelerates a rocket in outer space is exerted on the rocket by the

exhaust gasses

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

flying in different directions

Freddy Frog drops vertically from a tree onto a horizontally-moving skateboard. The reason he doesn't slip off the skateboard is due to

friction between his feet and the board

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

An astronaut floating alone in outer space throws a baseball. If the ball moves away at 20 m/s, the astronaut will

move in the opposite direction at a lower speed

A fan attached to an ice sailcraft stalled on a windless day blows air into the sail that bounces backward upon impact. The boat

moves in the direction of the impact force

A falling 1-N apple hits the ground with a force of about A) 2 N. B) 10 N. C) 1 N. D) 4 N. E) need more information

need more info

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

neither of these

The impulse-momentum relationship is a direct result of

newtons 2nd law

The conservation of momentum is most closely related to

newtons 3rd law

A sandbag motionless in outer space is hit by a three-times-as massive sandbag moving at 12 m/s. They stick together and move at a speed of A) 4 m/s. B) 8 m/s. C) 3 m/s. D) 6 m/s. E) none of the above

none of the above

Compared with falling on a stone floor, a wine glass may not break when it falls on a carpeted floor because the

stopping time is longer on the carpet

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

Two 5000-kg rail cars roll without friction (one at 1 m/s, the other at 2 m/s) toward each other on a level track. They collide, couple, and roll together with a combined momentum of

5000 kg 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

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?

6 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.

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

16 kg

A 5000-kg freight car moving at 2 m/s collides with a 10,000-kg freight car at rest. They couple upon collision and move away at

2 m/s

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

2000 N

The speed of a 4-kg ball with a momentum of 12 kg 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

3,000 kg m/s.

If all people, animals, trains and trucks all over the world began to walk or run towards the east (opposite the direction of Earth's spin), then

Earth would spin a bit slower.

It is correct to say that impulse is equal to

a corresponding change in momentum

When you jump from an elevated position you usually bend your knees upon reaching the ground, which makes the time of the contact about 10 times that of a stiff-legged landing. In this way the average force your body experiences is

about 1/10 as great

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

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) less stopping distance. C) more momentum. D) all of the above E) none of the above

all of the above

As Bronco Brown steps off a hovering high-flying helicopter and falls through the air, he experiences A) a decreasing acceleration . B) an increasing speed. C) an impulse. D) all of the above

all of the above

The force on a dropped apple hitting the ground depends upon A) the time of contact with the ground. B) whether or not the apple bounces. C) the speed of the apple just before it hits. D) all of the above

all of the above

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?

all the same

Two vehicles with equal magnitudes of momentum traveling at right angles to each other undergo an inelastic collision. The combined wreck moves in a direction

at 45 degrees to the direction of either car before collision.

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?

both are the same

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

decreases

When a vertically falling firecracker bursts, the vector sum of momentum fragments A) in the horizontal direction cancels to zero. B) in the vertical direction equals the momentum of the firecracker before bursting. C) both of these D) neither of these

both of these

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

both the same

You're driving down the highway and a bug spatters into your windshield. Which undergoes the greater change in momentum during the time of contact?

both the same

A karate chop is more effective if one's hand

bounces upon impact

The greater efficiency achieved with the curved blades of a Pelton wheel is due to

bouncing

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 cannon ball

A cannonball following a parabolic path explodes into fragments. The momentum of the fragments

continue along the path as if the explosion didn't occur.

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

decreased

An open freight car rolls friction free along a horizontal track in a pouring rain that falls vertically. As water accumulates in the car, the car's speed

decreases

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

Two vehicles with equal magnitudes of momentum traveling at right angles to each other undergo an inelastic collision. The magnitude of momentum for the combined wreck is

greater than the magnitude of momentum of either car before collision.

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 an falling object bounces from a surface

in an extended time

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 large heavy truck and a small baby carriage roll down a hill. Neglecting friction, at the bottom of the hill, the baby carriage will likely have

less momentum

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

If a monkey floating in outer space throws his hat away, the hat and the monkey will both

move away from each other but at different speeds

Two identical freight cars roll without friction (one at 1 m/s, the other at 2 m/s) toward each other on a level track. They collide, couple together, and roll away in the direction of

the faster car.

A karate expert executes a swift blow and breaks a cement block with her bare hand. The magnitude of the force on her hand is

the same as the force applied to the block

A tiny gun made of a strong but very light material fires a bullet more massive than the gun itself. For such a weapon

the target would be safer than the shooter

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

the time of contact is increased

When a boxer is moving away from a punch, the force experienced is reduced because

the time of contact is increased

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

Recoil is noticeable if we throw a heavy ball while standing on roller skates. If instead we go through the motions of throwing the ball but hold onto it, our net recoil will be

zero

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

zero