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Physics > Work, power and energy > Flashcards

Work, power and energy Flashcards

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0
Q

Unit energy is measured by.

A

Joules (j)

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1
Q

What is energy?

A

Energy is the ability to do work. Eg. move, heat.

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2
Q

Forms of energy

A

Potential, kinetic, heat, light, sound, electrical, chemical, nuclear.

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3
Q

Potential energy

A

This is energy stored that is just waiting to do work such as a coiled spring or elastic band.

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4
Q

Kinetic energy

A

The energy that moving things have. Eg. a windmill turning or a car moving.

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5
Q

Heat energy

A

(Eg. hot air rises)

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6
Q

Light energy

A

Light can move things in a Crookes Radiometer or in a solar powered calculator.

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7
Q

Sound energy

A

If you put your head near a loudspeaker you can feel that air is being moved by sound energy.

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8
Q

Electrical energy

A

Electricity is a flow of electrons around a circuit.

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9
Q

Chemical energy.

A

Food, fuel and batteries. This is the type of energy stored in fuels such as coal and oil, it is also stored in the food we eat and in batteries.

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10
Q

Nuclear energy

A

The energy stored in the nucleus of atoms.

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11
Q

Law of conservation of energy

A

energy cannot be created or destroyed, it can only be changed (converted) from one form to another.

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12
Q

What is insulation

A

Insulation is a method of keeping heat in.

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13
Q

Energy needs and heat loss.

A

We use energy in our homes to heat water and rooms and to work electrical appliances.

It is very important to try to save energy in the home.

Most of the heat energy in a house is lost.

Insulation is a method of keeping heat in. Eg. Drought excluder, double glazing, fibre goass, and lagging jacket.

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14
Q

Percentage of heat loss in a home.

A

Roof: 25%

Windows: 10%

Walls: 35%

Droughts: 15%

Floor: 15%

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15
Q

What is renewable energy?

A

Renewable energy is energy which can be replaced and does not run out.

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16
Q

What is non-renewable energy?

A

Non-renewable energy is energy that cannot be replaced and will run out. Eg. Coal, fuel, oil.

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17
Q

Types of renewable energy

A 
Solar
Hydro electric
Wind
Wave
Biomass
Geothermal
18
Q

Solar energy

A

Solar panels use the sun’s energy.

Eg. Solar panels using the sun’s energy to heat water.

19
Q

Hydro electric energy

A

Dams hold back water and then let it drop onto a wheel to turn a generator turbine to make electricity.

20
Q

Wind energy

A

Wind can turn windmills which generate energy.

21
Q

Wave energy

A

The movement of large floats by the energy in waves could be used to generate electricity.

22
Q

Biomass energy.

A

Some plants produce oils, others can produce fuels such as alcohol and methane gas.

23
Q

Geothermal energy.

A

The temperature under the Earth’s surface increase with depth. This heat can be used to heat water in some places.

24
Q

Advantages of Renewable Energy.

A

Renewable energy does not cause pollution.

They will not run out.

They are fairly safe to use.

25
Q

Disadvantages of renewable energy.

A

They are expensive go develop and set up.

More research needs to be done into how to make them good sources of energy.

Energy made may not be consistent in some forms. Eg. wind energy - the wind won’t always produce the same amount of energy.

Some pollution is produced when they are being created. Eg. when creating wind turbines.

26
Q

Types of non-renewable energy.

A

Fossil fuels (such as coal and oil), and nuclear energy,

27
Q

Fossil fuels.

A

Oil, coal, and natural gases are all examples of fossil fuels.

They were formed over millions of years from the bodies of dead plants and animals.

They cause pollution and damage the atmosphere.

28
Q

Nuclear energy.

A

When the nucleus of an atom is split, large amounts of energy are released from it.

If this energy is uncontrolled, dangerous explosions may happen.
If it is controlled, it can be used as a nuclear power station to make electricity.

29
Q

Advantages of nuclear energy.

A

In medicine, nuclear radiation is used to kill cancer cells.

Radiation can be used to sterilise food.

Radiation can produce electricity.

It will not run out like fossil fuels.

30
Q

Disadvantages of nuclear energy.

A

The waste products of nuclear energy are radioactive and are harmful to the environment as well as living things.

The waste products last in the environment for a long time.

If the nuclear energy gets out of control huge explosions my happen such as that in Chernobyl in 1986.

31
Q

What is work?

A

Work is done when a force moves an object.

32
Q

Work formula

A

Work (j) = force (n) x distance (m)

33
Q

Units of work

A

Newton meters (NM) or Joules (J)

34
Q

What is force?

A

A force is anything which causes an object to move or change it’s velocity.

35
Q

Units of force.

A

Newtons (N)

36
Q

What is weight?

A

Weight is a type of force. It is the gravitational force between the object and (for example) the Earth.

Remember: Mass is the amount of matter in an object.

37
Q

Weight formula.

A

Weight (N) = Mass (kg) x 10

38
Q

How much is a joule to a newton meter?

A

1 Joule = 1 Newton Meter.

39
Q

How do you convert cm to m?

A

To convert cm to m, divide by 100.

40
Q

Ways to save energy.

A

Transport - Walk, ride a bike, take the bus.

Lighting - use energy efficient lights, turn off lights when it’s bright.

Water heating - consider going solar for water heating systems, put timers on urns or use a kettle.

Equipment - Turn off computers when not in use.

41
Q

What is power?

A

Power is the rate at which work is done.

Power is a measure of how quickly energy is converted from one form to another.
Eg, if a light-bulb has a power rating of 40 watts, it is converting 40 joules of electrical energy into other types if energy (Mostly heat with only about 5% to light.)

42
Q

Unit of power.

A

The unit of power is the watt. (W)

Physics (14 decks)

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