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Physic
Q:
Which has the greater momentum when moving?
A) a container ship
B) a bullet
C) either of these depending on speed
Q:
Give two explanations of why a cannonball fired from a long-barrel cannon will have a greater velocity than from a shorter cannon.
Q:
Can an object have mechanical energy without having momentum? Can an object have momentum without having mechanical energy? Explain.
Q:
Why does the force of gravity do no work on a bowling ball rolling along a bowling lane? Look ahead to the next chapter and apply your explanation to satellite motion.
Q:
Discuss how energy conservation applies to a swinging pendulum. Where is potential energy the most? Where is it the least? Where is kinetic energy the most? Where is it the least? Where is the pendulum bob moving fastest? Where is it the slowest?
Q:
At the edge of a cliff you throw one ball downward and another ball upward at the same speed. Which will hit the ground faster? Does direction of the thrown ball make a difference? Explain.
Q:
Work is done on an object when you lift it against gravity. How does this work relate to gravitational potential energy? If the lifted object is dropped, what becomes of this energy?
Q:
A diesel locomotive coasting at 10 km/h has an inelastic collision with a stationary flatcar. The locomotive weighs four times as much as the flatcar. How fast does the locomotive-flatcar combination move when stuck together?
Q:
A boy fires a spring-loaded Ping-Pong ball gun. Briefly compare the forces and impulses on the gun and the ball. Which has more momentum? Which moves faster?
Q:
An unfortunate bug splatters on the windshield of a moving car. Describe the forces, impulses, momentum changes, and accelerations of both the bug and the car.
Q:
In terms of momentum, why is a drinking glass less likely to break if it falls on a carpeted floor than falling on a hard concrete floor?
Q:
The order in which solar energy is converted to the kinetic energy of an automobile is
A) photocells, electrolysis, motor, fuel cells, kinetic energy.
B) photocells, electrolysis, fuels cells, motor, kinetic energy.
C) electrolysis, fuel cells, photocells, motor, kinetic energy.
Q:
Hydrogen, like electricity, is
A) an energy source.
B) not an energy source.
C) a source of both thermal and electric power.
Q:
The fuel most likely to power tomorrow's scooters, forklifts, and busses is
A) hydrogen.
B) helium.
C) lithium.
Q:
Which of these is not a form of solar energy?
A) wind energy
B) fossil fuel energy
C) geothermal energy
D) hydroelectric power
Q:
The exhaust product from a hydrogen fuel cell is
A) carbon dioxide.
B) methane.
C) pure water.
D) nitric acid.
Q:
What is produced by the process of electrolysis?
A) energy
B) hydrogen and oxygen
C) pure drinking water
D) photovoltaic power
Q:
Solar power is commonly used to produce
A) heat.
B) electricity.
C) both of these
Q:
The ultimate source of energy from fossil fuels is the
A) Sun.
B) radioactivity in Earth's interior.
C) photosynthesis process.
D) natural processes in Earth's interior.
Q:
The source of Earth's internal energy involves
A) kinetic energy.
B) potential energy.
C) radioactivity.
D) the Sun.
Q:
The most energy per unit mass can be extracted from
A) coal.
B) petroleum.
C) natural gas.
D) uranium.
Q:
Which of these forms of energy is not renewable?
A) wind power
B) solar power
C) fossil fuel power
D) photovoltaic power
Q:
A common car engine is 20% efficient. When cruising, the car encounters an average retarding force of 1000 N. If the energy content of gasoline is 40 MJ/L, how many kilometers per liter does the car achieve?A) 14 km/LB) 12 km/LC) 10 km/LD) 8 km/LE) none of the above
Q:
Suppose a miracle car has a 100% efficient engine and burns fuel having an energy content of 40 MJ/L. If all resistant forces on this car traveling at highway speeds is 1000 N, what is the overall limit in distance per liter driven on the highway?
A) 30 km
B) 40 km
C) 50 km
D) more than 50 km
E) not enough information
Q:
If a power plant is 30% efficient, and the transmission system that delivers power to consumers is 60% efficient, then the overall efficiency is
A) 90%.
B) 60%.
C) 30%.
D) 18%.
E) none of the above
Q:
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
A) 10%.
B) 20%.
C) 50%.
D) 80%.
E) not enough information
Q:
A machine puts out 100 W of power for every 1000 W put into it. The efficiency of the machine is
A) 10%.
B) 50%.
C) 90%.
D) 110%.
E) none of the above
Q:
Although perpetual motion is the natural order of things in the universe
A) it follows that machines can operate and do work by perpetual motion.
B) no perpetual-motion device that multiplies energy exists.
C) both of these are false statements
Q:
Lifting a 100-N load with 50 N of force lifts it
A) half as high.
B) as high.
C) twice as high.
Q:
When a simple machine multiplies force, it decreases
A) potential energy.
B) distance moved.
C) both of these
D) none of the above
Q:
The most underlying feature of machines is
A) energy conservation.
B) that energy input always equals energy output.
C) that power input always equals power output.
D) all of the above
E) none of the above
Q:
A simple machine cannot multiply
A) force.
B) distance.
C) energy.
D) none of the above
Q:
A hydraulic jack is used to lift an automobile. If the input force is 200 N over a distance of 1 meter, the output force over a distance of 0.1 meter is ideally
A) 200 N.
B) 500 N.
C) 1000 N.
D) 2000 N.
E) none of the above
Q:
When a hydraulic press is properly used it is capable of multiplying force input.
A) true
B) false
C) true only in special cases, energy as well
Q:
A hydraulic press, like an inclined plane, is capable of increasing energy.
A) sometimes true
B) always false
C) always true
D) sometimes false
Q:
A pulley has two supporting strands. To lift a load 1 meter means you will have to pull a distance of
A) 1/2 m.
B) 1 m.
C) 2 m.
D) more than 2 m.
Q:
A pulley system can
A) change the direction of a force.
B) multiply a force.
C) both of these
D) none of the above
Q:
A common pulley acts similar to a
A) hydraulic press.
B) gear.
C) common lever.
D) tension producer.
Q:
A blob of material in outer space moves at 3 m/s when it collides and sticks to a half-as-massive blob initially at rest. Compared with the initial kinetic energy of the 3-m/s blob, the kinetic energy of the coupled blobs is
A) one-third.
B) two-thirds.
C) three-quarters.
D) not enough information
Q:
A piece of taffy slams into and sticks to another identical piece of taffy at rest. The momentum of the two pieces of taffy stuck together after the collision is the same as it was before the collision. Kinetic energy is a different story, for part of it turns into heat. What percentage of the kinetic energy converts into heat?
A) 0%
B) 25%
C) 50%
D) 75%
E) not enough information
Q:
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 violate the conservation of
A) momentum.
B) energy.
C) both of these
D) none of the above
Q:
You throw a golf ball at a massive bowling ball at rest and the golf ball bounces backward from it. After the bounce, compared with the golf ball, the bowling ball has more
A) momentum, but less kinetic energy.
B) kinetic energy, but less momentum.
C) momentum and more kinetic energy.
D) less momentum and less kinetic energy.
E) not enough information
Q:
Acrobat Bart at the circus drops vertically onto the end of a see-saw, with his partner Art equidistant from the fulcrum at the other end. Art is propelled straight upward a distance twice that of Bart's dropping distance. Neglecting inefficiencies we see
A) the masses of Art and Bart are equal.
B) Art has half the mass of Bart.
C) need more information
Q:
A circus diver drops from a high pole into water far below. When he is half-way down
A) his potential energy is halved.
B) he has gained an amount of kinetic energy equal to half his initial potential energy.
C) his kinetic and potential energies are equal.
D) all of the above
E) none of the above
Q:
When wind encounters a wind turbine that produces energy, wind speed on the downside of the blades is
A) slowed.
B) speeded up.
C) not affected.
Q:
Compared to a recoiling rifle, the bullet that is fired has a greater
A) momentum.
B) kinetic energy.
C) none of the above
Q:
From the edge of a roof you throw a snowball downward that strikes the ground with 100 J of kinetic energy. Then you throw a second snowball upward with the same initial speed, and this too falls to the ground. Neglecting air resistance, the second snowball hits the ground with a kinetic energy of
A) less than 100 J.
B) 100 J.
C) 200 J.
D) more than 200 J.
E) none of the above
Q:
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
A) 0.5 J.
B) 1.0 J.
C) 1.5 J.
D) 2.0 J.
E) more than 2.0 J.
Q:
A 2500-N pile driver ram falls 10 m and drives a post 0.1 m into the ground. The average force on the post is
A) 2500 N.
B) 25,000 N.
C) 250,000 N.
D) 2,500,000 N.
Q:
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
A) 1 N.
B) 10 N.
C) 20 N.
D) 21 N.
Q:
When Danny Diver who weighs 500 N steps off a diving board 10 m above the water, he hits the water with kinetic energy of
A) 10 J.
B) 500 J.
C) 510 J.
D) 5000 J.
E) more than 5000 J.
Q:
Strictly speaking, if any electrical device in an automobile is turned on (such as an air conditioner or even headlights), more fuel is consumed by the engine. This statement is
A) true.
B) true only if the engine is running.
C) always false.
D) sometimes true, sometimes false.
Q:
A block of ice sliding down an incline has one-quarter its maximum potential energy
A) one-quarter from the top.
B) one-quarter from the bottom.
C) three-quarters the way down.
D) need more information
Q:
A block of ice sliding down an incline has half its maximum kinetic energy
A) at the top.
B) at the bottom.
C) half-way down.
D) need more information
Q:
After rolling half-way down an incline, a marble's kinetic energy is
A) less than its potential energy.
B) greater than its potential energy.
C) the same as its potential energy.
Q:
The bob of a simple pendulum has its maximum kinetic energy at the
A) top of its swing.
B) bottom of its swing.
C) midpoint between top and bottom of its swing.
D) at all points along its path of swing.
Q:
A ball rolling down an incline has its maximum kinetic energy at
A) the top.
B) half-way down.
C) three-quarters of the way down.
D) the bottom.
Q:
A ball rolling down an incline has its maximum potential energy at
A) the top.
B) a quarter of the way down.
C) half-way down.
D) the bottom.
Q:
In raising a 5000-N piano with a pulley system, for every 1 m of rope pulled down, the piano rises 0.1 m. Ideally, this means the force needed to lift the piano is
A) 50 N.
B) 500 N.
C) 5000 N.
D) not enough information
Q:
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
A) the same distance.
B) twice as deep.
C) three times as deep.
D) more than three times as deep.
Q:
Two identical arrows, one with twice the speed of the other are fired into a bale of hay. The faster arrow will penetrate the bale
A) the same distance as the slower arrow.
B) twice as far as the slower arrow.
C) four times as far as the slower arrow.
D) more than four times as far as the slower arrow.
E) none of the above
Q:
Which requires more work on the brakes of a car?
A) slowing down from 100 km/h to 70 km/h
B) slowing down from 70 km/h to a stop
C) equal amounts of work for either
Q:
A car that travels twice as fast as another car when braking to a stop will skid
A) twice as far.
B) four times as far.
C) depends on the mass of the cars.
Q:
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?
A) 20 m
B) 60 m
C) 90 m
D) 180 m
Q:
A ball is projected into the air with 900 J of kinetic energy that is transformed to potential energy at the top of its trajectory. When it returns to its original level after encountering air resistance, its kinetic energy is
A) less than 900 J.
B) more than 900 J.
C) 900 J.
D) not enough information
Q:
A car moves 4 times as fast as another identical car. Compared with the slower car, the faster car has
A) 4 times the kinetic energy.
B) 8 times the kinetic energy.
C) 12 times the kinetic energy.
D) 16 times the kinetic energy.
Q:
No work is done by gravity on a bowling ball that rolls along a bowling alley because
A) no force acts on the ball.
B) no distance is covered by the ball.
C) the force on the ball is at right angles to its motion.
D) no potential energy converts to kinetic energy.
E) its kinetic energy may vary.
Q:
When a bus brakes to a stop its kinetic energy transforms to
A) stopping energy.
B) potential energy.
C) energy of motion.
D) energy of rest.
E) heat.
Q:
Which has the greater kinetic energy?
A) a car traveling at 30 km/h
B) a car of half the mass traveling at 60 km/h
C) both the same
D) need more information
Q:
The power expended for a barbell raised 2.0 m in 2 s is
A) 1 W.
B) 4 W.
C) 8 W.
D) not enough information
Q:
A 50-kg sack is lifted 2 m in the same time as a 25-kg sack is lifted 4 m. The power expended in raising the 50-kg sack compared to the power used to lift the 25-kg sack is
A) twice as much.
B) half as much.
C) the same.
Q:
Which requires more work: lifting a 50-kg sack vertically 2 m or lifting a 25-kg sack vertically 4 m?
A) lifting the 50-kg sack
B) lifting the 25-kg sack
C) both require the same amount of work
Q:
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?
A) 20 W
B) 50 W
C) 100 W
D) 1000 W
E) 20,000 W
Q:
If you exert 100 J to lift a box in 50 s your power output is
A) 1/4 W.
B) 1/2 W.
C) 2 W.
D) 4 W.
E) more than 4 W.
Q:
If you exert 6 N across a distance of 2 m in 3 s you'll deliver a power of
A) 1 W.
B) 3 W.
C) 4 W.
D) 6 W.
E) more than 6 W
Q:
If you do work on an object in half the time, your power output is
A) half.
B) the same.
C) twice.
Q:
You do work on a cart loaded with groceries. If you do this work in one-third the usual time, you expend
A) one third as much power.
B) the usual power.
C) three times the usual power.
D) need more information.
Q:
Power is defined as the
A) force exerted divided by the time of exertion.
B) force exerted multiplied by the distance moved.
C) work done multiplied by the time to do the work.
D) work done divided by the time to do the work.
E) none of the above
Q:
A cat and a mouse run along a road with the same kinetic energy. The faster runner is the
A) cat.
B) mouse.
C) both run at the same speed
D) not enough information
Q:
A shopping cart moves with a kinetic energy of 40 J. If it moves at twice the speed, its kinetic energy is
A) 40 J.
B) 80 J.
C) 160 J.
D) not enough information