Conceptual Physics -- Chapter 6: Momentum

see sheet #45

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A 10-kg cement block moving horizontally at 6 m/s plows into a bank of sand and comes to a stop 2 s. What is the average impact force on the bank?

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A 1-kg chunk of putty moving at 1 m/s collides with 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

An 8-kg blob of clay moving horizontally at 2 m/s hits a 3-kg blob of clay at rest. What is the speed of the two blobs stuck together immediately after the collision?

1.45 m/s

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

1/2 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 5000-kg freight car moving at 2 m/s collides with a 10000-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

3000 kg m/s

A ball is moving at 6.0 m/s and has a momentum of 24.0 kg m/s. What is the ball's mass?

4.0 kg

What is the average momentum of a 50-kg skateboarder who covers 400 m in 50 s?

400 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

A 5000-kg freight car collides with a 10000-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

It is correct to say that impulse is equal to

a corresponding change in momentum

A collision is considered elastic if

all of the above

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 choices

The force on a dropped apple hitting the ground depends upon

all of the choices

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

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

both the same

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 cannonball

You're driving down the highway and a bug spatters into your windshield. Which undergoes the greater change in momentum of the airplane is

decreased

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

decreases

A freight train rolls along a track with considerable momentum. If it were to roll at the same speed but had twice as much mass, its momentum would be

doubled

Which has greater momentum when moving?

either of these depending speed

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

equal the momentum of the firecracker at the time of burst

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

The momentum change of an object is equal to the

impulse acting on it

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

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

longer time

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 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

none of these

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

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 force applied to the block

In order to catch a ball, a baseball player moves his or her hand backward in the direction of the ball's motion. Doing this reduces the force of impact on the player's hand principally because

the time of impact is increased

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

twice

Compared to a sports car moving at 30 miles per house, the same sports car moving at 60 miles per hour has

twice as much momentum

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

zero