Chapter 3

Two billiard balls having the same mass roll toward each other at the same speed. What is the net momentum of the two-ball system?

0 kg•m/s

A 30-kg girl and a 25-kg boy face each other on friction-free roller blades. The girl pushes the boy, who moves away at a speed of 1.0 m/s. The girl's speed is

0.83 m/s

Exert 1 N for a distance of 1 m in 1 s and you deliver a power of

1 W

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

1 unit

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

1/2 m/s

A 1-kg chunk of putty moving at 1 m/s collides with and sticks to a 5-kg bowling ball that is initially at rest in space. The bowling ball and putty are then set in motion with a speed of

1/6 m/s

Consider 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, which has a mass of 5 kg and is at rest. If they stick upon collision the speed the combined gliders will be

1/6 m/s

A ball is moving at 4 m/s and has a momentum of 48 kg•m/s. What is the ball's mass?

12 kg

A car moves 4 times as fast as another identical car. Compared with the slower car, the faster car has

16 times the kinetic energy

A shopping cart moves with a kinetic energy of 40 J. If it moves at twice the speed, its kinetic energy is

160 J

A car moving at 50 km/h skids 20 m with locked brakes. How far will it skid if its initial speed is 150 km/h?

180 m

When the input piston of a hydraulic press is depressed 20 cm, the output piston is observed to move 1 cm. An input force of 1 N can raise no more than

20 N

A 1000-kg car moving at 10 m/s that brakes to a stop in 5 s has an average braking force of

2000 N

A music console is pushed a distance of 2 m with a force of 20 N. The work done on the console is

40 J

Suppose a miracle car has a 100% efficient engine and burns fuel having an energy content of 40 MJ/L. If the air resistance and overall frictional forces on this car traveling at highway speeds is 1000 N, what is the overall limit in distance per liter driven on the highway?

40 km

A 5-kg fish swimming at a speed of 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

Using 1000 J of work, a toy elevator is raised from the ground floor to the second floor in 20 s. How much power does the elevator use?

50 W

A jack system will increase the potential energy of a heavy load by no more than 1000 J with a work input of 2000 J. The efficiency of the jack system is at most

50%

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

6 m/s

A 2-kg mass weighs 20 N and is held 4 m above the ground. Its potential energy relative to the ground is

80 J

Which of the following has the largest momentum relative to Earth?

a pickup truck speeding along a highway

The massive ram of a pile driver falling from rest strikes a pile with a speed that depends on the

all of above

A moving object has

all the above

Padded dashboards in cars are safer in an accident than non-padded ones because an occupant hitting the dash has

both

Which requires more work: lifting a 50-kg sack vertically 2 m or lifting a 25-kg sack vertically 4 m?

both require the same amount of work

You're driving down the highway and a lovebug spatters onto your windshield. Which undergoes the greater change in momentum?

both the same

An open freight car rolls friction-free along a horizontal track in vertically pouring rain. As water accumulates in the car, its speed

decreases

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

decreases

Whereas impulse involves the time that a force acts, work involves the

distance that a force acts

A popular swinging-balls apparatus (Newton's cradle) consists of a series of identical elastic balls suspended by strings so they barely touch each other. When two balls are pulled away from one end and released, they strike the row of balls and two balls pop out from the other end. If instead, one ball popped out with twice the speed, this would be a violation of conservation of

energy

Which of these forms of energy is NOT renewable?

fossil fuel power

A car that travels twice as fast as another car when braking to a stop will skid

four times as far

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 to stop the car, the force needed to stop the truck is

greater

When an apple falls to the ground, momentum is transferred to the ground. The momentum absorbed by the ground is

greater than that of the apple if the apple bounces

Lifting a 100-N load with 50 N of force lifts it

half as high

A clerk can lift containers a vertical distance of 1 m, or roll them up a 2-m-long ramp to the same elevation. With the ramp, the applied force needed is

half as much

When a non-hybrid car brakes to a stop its kinetic energy transforms to

heat

The speed of a bullet fired from a gun will be about the same as the speed of the recoiling gun

if the masses of the bullet and gun are equal

A cannonball fired from a long-barrel cannon will have a greater muzzle velocity because the cannonball receives a greater

impulse

Compared to a recoiling rifle, the bullet that is fired has a greater

kinetic energy

When you are in the way of a fast-moving object and can't get escape, you will suffer a smaller force if the collision time is

long

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

longer time to stop

When a cannon fires a cannonball at a given speed, the smaller recoil speed of the cannon is due to different

masses

A heavy truck and a small truck roll down a hill. Neglecting friction, at the bottom of the hill the heavy truck has greater

momentum

An object in motion will continue in motion with

momentum

A 1-kg ball dropped from a height of 2 m rebounds only 1.5 m after hitting the ground. The amount of energy converted to heat is about

more than 2.0 J

A boulder is dropped onto mud and plows into it a certain distance. If it hits with three times as much speed, the distance it plows into the mud will likely be

more than three times as deep

An object that has kinetic energy must be

moving

A sandbag is motionless in outer space. A second sandbag with 3 times the mass moving at 12 m/s collides with it and they both stick together and move at a speed of

none of the above

The power expended for a barbell raised 2.0 m in 2 s is

not enough information

The source of Earth's internal energy involves

radioactivity

It is correct to say that impulse is equal to

the change in momentum

The most underlying feature of machines is

the conservation of energy

Consider driving into a massive concrete wall with no "give," versus having a head-on collision at the same speed with an identical car moving toward you at the same speed. It would be more damaging to hit the

the same

In order to catch a fast-moving softball with your bare hand, you extend your hand forward just before the catch and then let the ball ride backward with your hand. Doing this reduces the catching force because the

time of catch is increased

Strictly speaking, if any electrical device in an automobile is turned on (such as an air conditioner, headlights, or radio), more fuel is consumed by the engine. This statement is

true

An object lifted 10 m gains a certain amount of potential energy. If it is lifted 20 m, its gain in potential energy is

twice as much

If you push an object twice as far while applying the same force, you do

twice as much work

A sandbag in outer space moves at 3 m/s when it collides and sticks to a half-as-massive sandbag initially at rest. Compared with the kinetic energy of the moving sandbag before collision, the kinetic energy of the coupled sandbags after collision is

two-thirds