Chapter 6 Physics

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

0.5 m/s

A 1kg chunk of putty moving at 1 m/s collides with and sticks to a 5kg 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 fire 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 nd 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 stetch is 2 s while coming to a halt, the jumpers 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 1m/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

The conservation of momentum is closely related to

Newton's third law

The impulse-momentum relationship is a direct result of

Newtons 2nd law

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

a pickup truck speeding along a highway

A firecracker bursts while freely falling. The combined momentum of its fragments

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 gases

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 te 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 sail craft stalled on a windless day blows air into the sail that bounces backward upon impact. The boat

moves in the direction of the wind impact force

A falling 1-N apple hits the ground with a force of about

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

neither of these

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

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

Which has a greater momentum when moving?

either of these depending on speed

A 5kg 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 10,000-kg freight car at rest. They couple upon collision and move at 2m/s. What was the initial speed of the 5000-kg car?

6m/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, then

Earth would spin a bit slower

When a vertically falling firecracker bursts, the vector sum of momentum fragments

both of these

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

all of the above

As Bronco Brown steps off a hovering high-flying helicopter and falls through the air, he experiences

all of the above

The force on a dropped apple hitting the ground depends upon

all of the above

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

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

decreases

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

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?

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 acheived with the curved blades of a Pelton wheel is due to

bouncing

A cannonball 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

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 freee aliong a horizontal trak in a pouring rain that falls vertically. As water accumulates in the car, the car's speed...

decreases

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

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 complete 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 a 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

Two identical freight cars roll without friction towards each other on a level track. One car rolls at 2 m/s and the other car rolls at 1 m/s. They collide, couple, and roll away in the direction of

the faster car

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

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

the time of contact is increased

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

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 you throw a heavy ball while standing on roller skates. If instead you go through the motions of throwing the ball but hold onto it, your 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