Energy And Efficiency Flashcards

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1
Q

What form of energy does a compressed spring have?

A

Elastic potential energy

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2
Q

What happens when an object falls and gains speed?

A

It’s gravitational potential energy decreases and it’s kinetic energy increases.

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3
Q

Where does the chemical energy stored in your muscles come from?

A

From the food that you eat

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4
Q

It is not possible to create or destroy energy. What is it possible to do?

A

To transfer energy from one form to another or one place to another

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5
Q

What is the conservation of energy?

A

It means that the total amount of energy is always the same. And this applies to all energy transfers.

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6
Q

What is transferred in a solar cell?

A

Light energy is transferred to electrical energy.

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7
Q

In terms of energy what happens when you burn a fuel?

A

Chemical energy in the fuel is transferred to the surrounding which get warmer.

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8
Q

What energy transfers take place when you turn on a torch?

A

Chemical to electrical to light and transfer by heating.

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9
Q

What does a swinging pendulum transfer?

A

It transfers energy from gravitational potential energy to kinetic energy and back again as it swings.

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10
Q

Out of a machine what types of energy do we get?

A

Useful and wasted energy

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11
Q

What is useful and wasted energy?

A

Useful- transferred to the place we want and in the form we want.
Wasted- not usefully transferred.

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12
Q

Where do both energies go to?

A

They both end up being transferred to the surroundings which become warmer.

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13
Q

What happens to the wasted energy from a light bulb?

A

Transferred to surroundings which gets warmer.

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14
Q

Why should we talk about energy being wasted not energy being lost?

A

Because the law of conservation tells us that energy cannot be destroyed.

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15
Q

Fill I’m:

The ______ energy that is wasted by the machine the more efficient.

A

Less

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16
Q

What does the efficiency equal?

A

Useful energy transferred / total energy supplied X 100

17
Q

In a light bulb for every 25 joules of energy that are supplied to the bulb ,5 joules are usefully transferred into light energy. What is the efficiency of the bulb ?

A

20%

18
Q

A machine is adjusted so that it wastes less energy because of friction. What happens to the efficiency of the machine?

A

It increases

19
Q

What form of energy does a moving car have?

A

Kinetic energy

20
Q

What form of energy does a stretched spring have?

A

Elastic potential energy

21
Q

When is electrical energy transferred?

A

When an electric current flows.

22
Q

What are the useful energy transfer in a hairdryer?

A

Electrical to kinetic and energy transferred by heating

23
Q

What are the useful energy transfers in a television?

A

Electrical to light and sound

24
Q

What energy transfers take place when you lift a ball into the air and then drop it so it falls to the ground?

A

Kinetic to gravitational potential energy to kinetic

25
Q

Wear and tear causes damage to waste more energy. What happens to the efficiency of this machine?

A

It decreases

26
Q

Why is an electric heater the only appliance that may have an efficiency of 100%?

A

Because it is designed to transfer energy by heating which is normally how appliances waste energy.

27
Q

What forms can energy exist in ?

A
Light  
Sound
Kinetic
Nuclear
Electrical
Gravitational potential
Elastic
Chemical