Physics Test 3: Kinetic Energy Concepts

Questions and Answers

An object that has kinetic energy must be?

moving

A cannonball has more kinetic energy than the recoiling cannon from which it is fired because the force on the ball?

acts over a longer distance.

If you do work on a skateboard loaded with friends in one-third the usual time, you expend?

three times the usual power.

A roller skate at rest may have?

potential energy. Signup and view all the answers

The work you do when pushing a shopping cart twice as far while applying twice the force is?

four times as much. Signup and view all the answers

A motorcycle moving at 50 km/h skids 10 m with locked brakes. How far will it skid with locked brakes when traveling at 150 km/h?

90 m Signup and view all the answers

A light aluminum ball and a heavy lead ball of the same size roll down an incline. When they are halfway down the incline, they will have identical?

none of the above Signup and view all the answers

Two identical golf carts move at different speeds. The faster cart has twice the speed and therefore has?

four times the kinetic energy. Signup and view all the answers

The work you do when pushing a shopping cart a given distance while applying twice as much force is?

twice as much. Signup and view all the answers

A bicycle that travels four times as fast as another when braking to a stop will skid?

sixteen times as far. Signup and view all the answers

A car's engine is 20% efficient. When cruising, the car encounters an average retarding force of 1000 N. If the energy content of fuel is 40 megajoules per liter, how many kilometers per liter does the car achieve?

8 Signup and view all the answers

After rolling halfway down an incline, a marble's kinetic energy is?

the same as its potential energy. Signup and view all the answers

Which task requires more work?

both require the same. Signup and view all the answers

A melon is projected into the air with 100 J of kinetic energy in the presence of air resistance. When it returns to its initial level its kinetic energy is?

less than 100 J. Signup and view all the answers

A ball rolling down an incline has its maximum potential energy at?

the top. Signup and view all the answers

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

four times as far. Signup and view all the answers

A 1-kg ball dropped from 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. Signup and view all the answers

A hydraulic jack is used to lift objects such as automobiles. 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?

2000 N. Signup and view all the answers

The work done in pushing a TV set a distance of 2 m with an average force of 20 N is?

40 J. Signup and view all the answers

A hydraulic press has its input piston depressed 20 centimeters while the output piston is raised 1 centimeter. A 1-newton input can lift a load of?

20 N. Signup and view all the answers

A jack system will increase the potential energy of a heavy load by 1000 J with a work input of 2000 J. The efficiency of the jack system is?

50%. Signup and view all the answers

If the speed of a bicycle is reduced to half before skidding to a stop, it will skid?

one-fourth as far. Signup and view all the answers

Both a 50-kg sack lifted 2 meters from the ground and a 25-kg sack lifted 4 meters in the same time. The power expended in raising the 50-kg sack is?

the same. Signup and view all the answers

A moving object has?

all of these. Signup and view all the answers

The power required to exert 4-N force over 3 meters in 2 seconds is?

6 W. Signup and view all the answers

When a drawn bow of potential energy 40 J is fired, the arrow will ideally have a kinetic energy?

of 40 J. Signup and view all the answers

Neglecting air resistance, Sammy Smarts on a high ladder releases a ball that strikes the ground with 100 J of kinetic energy. If he were to instead throw the ball straight upward, it will soon reach the ground with a kinetic energy of?

100 J. Signup and view all the answers

A 1000-kg car and a 2000-kg car are hoisted to the same height. Raising the more massive car requires?

twice as much work. Signup and view all the answers

Impulse involves the time that a force acts, whereas work involves the?

distance that a force acts. Signup and view all the answers

A clerk can lift cylindrical packages 1 meter vertically, or can roll them up a 2-meter-long ramp to the same elevation. With the ramp, the applied force required is about?

half as much. Signup and view all the answers

The unit kilowatt-hour is a unit of?

energy. Signup and view all the answers

About 40 J is required to push a crate 4 m across a floor. If the push is in the same direction as the motion of the crate, the force on the crate is about?

10 N. Signup and view all the answers

The power expended doing 100 J of work in 50 s is?

2 W. Signup and view all the answers

A crate of grapes lifted 10 meters gains 200 J of potential energy. If the same crate is instead lifted 20 meters, its gain in potential energy is?

twice as much. Signup and view all the answers

If an all-electric car has kinetic energy, then it also must have?

momentum. Signup and view all the answers

A machine puts out 100 watts of power for every 1000 watts put into it. The efficiency of the machine is?

10%. Signup and view all the answers

Strictly speaking, more fuel is consumed by your car if the air conditioner, headlights, or even a radio is turned on.

True Signup and view all the answers

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?

Art has half the mass of Bart. Signup and view all the answers

No work is done by gravity on a bowling ball that rolls along a bowling alley because?

True Signup and view all the answers

The bob of a simple pendulum has its maximum kinetic energy at the?

bottom of its swing. Signup and view all the answers

Which has greater kinetic energy?

a car of half the mass traveling at 60 km/h. Signup and view all the answers

The amount of work done on a heavy box carried by Nellie across a room at a constant speed?

is none. Signup and view all the answers

One kilowatt-hour represents?

3.6 million joules. Signup and view all the answers

A melon is tossed straight upward with 100 J of kinetic energy. If air resistance is negligible the melon will return to its initial level with a kinetic energy of?

100 J. Signup and view all the answers

The work you do when pushing a shopping cart twice as far while applying the same force is?

twice as much. Signup and view all the answers

When you and your snowboard are in motion, which of the following can be zero?

none of the above. Signup and view all the answers

The ram of a pile driver drops onto the top of an iron beam, driving it partway into the ground. The distance that the beam sinks into the ground depends on the?

all of the above. Signup and view all the answers

Relative to an initial height, an object raised twice as high has a gravitational potential energy?

twice as much. Signup and view all the answers

If a Ping-Pong ball and a golf ball both move in the same direction with the same amount of kinetic energy, the speed of the Ping-Pong ball must be?

more than the golf ball. Signup and view all the answers

A primary difference between momentum and kinetic energy is?

momenta can cancel; kinetic energy cannot. Signup and view all the answers

A block of ice sliding down an incline has half its maximum kinetic energy?

halfway down. Signup and view all the answers

Two identical arrows, one with twice the speed of the other, are fired into a bale of hay. Compared with penetration of the slow arrow, the faster arrow penetrates?

four times as far. Signup and view all the answers

A circus diver drops from a high pole into water far below. When he is halfway down?

all of the above. Signup and view all the answers

A 2500-N pile-driver ram falls 10 m and drives a post 0.1 m into the ground. The average impact force on the ram is?

250,000 N. Signup and view all the answers

When wind encounters a wind turbine that produces energy, wind speed on the downside of the blades is?

slowed. Signup and view all the answers

Which requires the most amount of work by the brakes of a car?

slowing down from 100 km/h to 70 km/h. Signup and view all the answers

An object has gravitational potential energy due to its?

location. Signup and view all the answers

When Joshua brakes his speeding bicycle to a stop, kinetic energy is transformed to?

heat. Signup and view all the answers

Danny Diver weighs 500 N and steps off a diving board 10 m above the water. Danny hits the water with kinetic energy of?

5000 J. Signup and view all the answers

Two identical particles move toward each other, one twice as fast as the other. Just before they collide, one has a kinetic energy of 25 J and the other 50 J. At this instant their total kinetic energy is?

75 J. Signup and view all the answers

Two identical arrows, one with twice the kinetic energy of the other, are fired into a bale of hay. Compared with penetration of the slow arrow, the faster arrow penetrates?

twice as far. Signup and view all the answers

A 2-kg box of taffy candy has 40 J of potential energy relative to the ground. Its height above the ground is?

2 m. Signup and view all the answers

A 2-kg ball is held 4 m above the ground. Relative to the ground its potential energy is?

80 J. Signup and view all the answers

A toy elevator is raised from the ground floor to the second floor in 20 seconds. The power needed using 1000 J of work, is?

50 W. Signup and view all the answers

A ball rolling down an incline has its maximum kinetic energy at?

the bottom. Signup and view all the answers

Tomatoes have a higher specific heat capacity than dough. This means that when you bite into a hot pizza?

the tomato sauce feels hotter than the dough. Signup and view all the answers

The specific heat capacity is highest for substances that absorb or release large quantities of heat for correspondingly?

small temperature changes. Signup and view all the answers

A substance that heats up relatively slowly has a?

high specific heat capacity. Signup and view all the answers

Aluminum has a higher specific heat capacity than iron. This means that for equal masses of aluminum and iron, the metal that heats more quickly when the same amount of heat is applied is?

iron. Signup and view all the answers

Place a 1-kilogram block of iron at 40°C into 1 kilogram of water at 20°C and the final temperature of the two becomes?

less than 30 degrees Celsius. Signup and view all the answers

Heat energy travels from an object with a high?

temperature to an object with a lower temperature. Signup and view all the answers

Which unit represents the most energy?

Calorie. Signup and view all the answers

Compared to a giant iceberg, a hot cup of coffee has?

higher temperature, but less internal energy. Signup and view all the answers

The quantity of heat that a substance can transfer relates to its?

all of the above. Signup and view all the answers

Which temperature scale has the smallest sized degrees?

Fahrenheit. Signup and view all the answers

Temperature is most closely related to molecular?

kinetic energy. Signup and view all the answers

The amount of heat needed to raise the temperature of 1 gram of water by 1°C is?

4.19 Joules. Signup and view all the answers

If the specific heat capacity of water were lower than it is, a nice hot bath would be a?

shorter experience. Signup and view all the answers

Room temperature on the Kelvin scale is about?

300 K. Signup and view all the answers

The fact that desert sand is very hot in the day and very cold at night is evidence that the specific heat capacity of sand is relatively?

low. Signup and view all the answers

When 10 grams of hot water cool by 1°C, the amount of heat given off is?

41.9 Joules. Signup and view all the answers

A temperature difference of 10 Celsius degrees is also equal to a temperature difference of 10 on the?

Kelvin scale. Signup and view all the answers

The air in your room is composed of molecules that have?

a wide variety of speeds. Signup and view all the answers

Heat energy is measured in units of?

both of these. Signup and view all the answers

In which is the temperature greater?

both the same. Signup and view all the answers

Which temperature scales have equal sized degrees?

Celsius and Kelvin. Signup and view all the answers

Aluminum has a specific heat capacity more than twice that of copper. Place equal masses of aluminum and copper wire in a flame and the one to undergo the fastest increase in temperature will be?

copper. Signup and view all the answers

The fact that a thermometer 'takes its own temperature' illustrates?

thermal equilibrium. Signup and view all the answers

Pour a liter of water at 40°C into a liter of water at 20°C and the final temperature of the two becomes?

at or about 30 degrees Celsius. Signup and view all the answers

Pour two liters of water at 40°C into one liter of water at 20°C and the final temperature of the two becomes?

more than 30 degrees Celsius. Signup and view all the answers

One of water's interesting thermal properties is that when heated it takes a relatively?

long time in changing temperature. Signup and view all the answers

A substance that heats up relatively quickly has a?

low specific heat capacity. Signup and view all the answers

When you touch a cold piece of ice with your finger, energy flows?

from your finger to the ice. Signup and view all the answers

When you touch a hot potato with your finger, energy flows?

from the potato to your finger. Signup and view all the answers

If the specific heat of water were lower than it is, ponds in the cold winter would be?

more likely to freeze. Signup and view all the answers

Which of the following normally warms up fastest when heat is applied?

iron. Signup and view all the answers

If the specific heat capacity of water were lower than it is, a watermelon in a picnic cooler would cool in a?

shorter time. Signup and view all the answers

A substance that cools down faster than others has a?

low specific heat capacity. Signup and view all the answers

The white-hot sparks from a 4th-of-July-type sparkler that strike your skin transfer?

little energy to you in spite of their high temperature. Signup and view all the answers

The moderate temperatures of islands throughout the world have much to do with water's?

high specific heat capacity. Signup and view all the answers

Study Notes

Kinetic Energy and Work

An object with kinetic energy is moving.
A cannonball possesses more kinetic energy than the recoiling cannon due to the force acting over a longer distance.
Performing work on a skateboard loaded with friends in one-third the usual time results in three times the typical power exerted.
A roller skate at rest contains potential energy.
Pushing a shopping cart twice as far while applying double the force leads to four times the work done.
A motorcycle traveling at 150 km/h will skid 90 m with locked brakes, much more than at a lower speed.
Identical objects rolling down an incline have varying forms of energy; their energies are not identical halfway down.
A faster golf cart moving at double speed has four times the kinetic energy compared to a slower one.
If a bicycle travels twice as fast when skidding, it will skid sixteen times farther.
A car with a 20% efficient engine experiences a retarding force of 1000 N, achieving 8 km per liter of fuel.

Energy Transformation and Conservation

After rolling halfway down an incline, a marble has the same kinetic energy as its initial potential energy.
A melon projected with 100 J of kinetic energy loses energy due to air resistance upon returning to its initial height.
Potential energy is maximized at the top of an incline and is transformed fully to kinetic at the bottom.
A 1-kg ball dropped from 2 m rebounds, converting about more than 2.0 J of energy to heat.
Using a hydraulic jack, the output force is significantly higher (2000 N) compared to the input force (200 N) over different distances.

Calculating Power and Efficiency

The work done in pushing a television for 2 m with an average force of 20 N equals 40 J.
Hydraulic systems can amplify force, allowing for heavy loads to be lifted effectively.
The efficiency of a jacking system that raises 1000 J of potential energy with 2000 J of work input is 50%.
If a speed decreases to half, the distance skidded will be reduced to one-fourth compared to its original distance.

Work and Energy in Various Contexts

The gravitational potential energy of an object depends on its height from the ground.
The relationship between momentum and kinetic energy shows that while momenta can cancel, kinetic energy cannot.
Impulse involves the force acting over time, while work will consider the distance the force acts upon.
Kinetic energy transformation occurs during braking; kinetic energy is transformed to heat.

Thermal Properties and Heat Transfer

Specific heat capacity dictates how substances respond to heat; materials like aluminum heat up quickly compared to others like water.
Heat energy naturally transfers from higher to lower temperatures, balancing thermal equilibrium.
Room temperature is approximately 300 K on the Kelvin scale.
A lower specific heat capacity means a substance will change temperature more quickly.
The amount of heat required to raise the temperature of 1 g of water by 1°C is 4.19 Joules.

Practical Implications of Heat and Energy

The unique thermal properties of water contribute to moderate island temperatures due to its high specific heat capacity.
The temperature difference between scales like Celsius and Kelvin is interchangeable for small differences.
The energy flow, when touching objects at different temperatures, is always from the hotter to the cooler object.
Ponds would be more likely to freeze if water had a lower specific heat capacity, illustrating the importance of water's thermal properties in environmental contexts.

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This quiz focuses on key concepts related to kinetic energy, exploring definitions and principles through flashcards. Test your understanding of how kinetic energy applies in various scenarios, such as moving objects and the effects of force and distance.