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Science Y9 > Energy > Flashcards

Energy Flashcards

1
Q

What can energy NOT do?

A

be used up/destroyed

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2
Q

what can energy do

A

be stored and transferred

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3
Q

___ can be ___or ___ but it cannot be ___ ___.

A

Energy can be stored or transferred but it cannot be used up.

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4
Q

define energy

A

the ability that something has to do work.

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5
Q

how does energy exist

A

Energy exists as different stores inside a system.

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6
Q

what is a system

A

object or a group of objects

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7
Q

what are the seven energy stores?

A

thermal, Chemical, Kinetic, Elastic potential, Gravitational Potential, Magnetic, Electrostatic

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8
Q

how many ways can energy be transferred

A

4 main ways

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9
Q

what are the 4 main ways energy can be transferred

A

electrically, mechanically, heat, light & sound

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10
Q

describe energy transfer via electricity

A

When electrons move this creates an electrical circuit and causes them to have an electrical charge.

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11
Q

describe mechanical energy transfer

A

When a force makes something move.

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12
Q

describe energy transfer via heat

A

When energy is transferred from hotter objects to colder objects via conduction, convection and radiation

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13
Q

describe energy transfer via sound

A

Sound energy is transferred through the substance in a wave.

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14
Q

what energy store does a solar panel turn light energy into

A

electrical energy

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15
Q

what energy store does a chemical reaction turn chemical energy into

A

kinetic, sound, thermal, and light energy

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16
Q

what energy store does a microphone turn sound energy into

A

electrical energy

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17
Q

what energy store does a rocket turn chemical energy via kinetic energy into

A

gravitational potential energy

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18
Q

what is the flowchart for energy transformation?

A

input = useful output + wasted output

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19
Q

what is the Law of conservation of energy:

A

Energy cannot be created or destroyed, but it can be

transferred or transformed from one form to another.

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20
Q

a television. write a flowchart for energy transformation for a tv.

A

electrical energy = light, sound + heat

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21
Q

what does a device do?

A

changes energy from one form to another.

22
Q

define efficiency

A

the ability to avoid wasting materials, energy, efforts, money, and time in doing something. if a device works at its maximum output without or with very little wasted energy, it is efficient.

23
Q

what is energy transformation

A

any process of transforming one form of energy into another.

24
Q

what is energy transfer

A

the process of transferring energy from one body to another – the movement of energy.

25
Q

what does a sankey diagram represent

A

the energy transfer and transformation through a device

26
Q

energy input must equal what

A

energy output

27
Q

what does the width and length of an arrow on a sankey diagram tell you

A

the width demonstrates the amount of energy. the length has no significance.

28
Q

true or false: The greater the percentage of energy that is transformed into useful energy in a device, the
more efficient a device is.

A

true

29
Q

true or false: The lesser the percentage of energy that is transformed into useful energy in a device, the
more efficient a device is.

A

false

30
Q

what equation is used to calculate the efficiency of a device

A

Efficiency =
Useful energy transferred (output)
___________________________
Total energy supplied (input)

31
Q

how can efficiency be written

A

as either a number (which is never more than 1) or as a percentage (never more than 100%). Neither have units.

32
Q

what are fossil fuels

A

Fuels formed over millions of years from dead

animals and plants.

33
Q

what type of resource are fossil fuels

A

non-renewable

34
Q

what are 3 fossil fuels

A

crude oil, coal, and natural gas

35
Q

how is coal formed

A

Trees and animals die and decompose -> layers of sand and mud -> heat and pressure -> layers of coal are formed

36
Q

How is energy generated from non-renewable

resources?

A
  1. The fuel is burned to boil water to make steam.
  2. The steam makes a turbine spin.
  3. The spinning turbine turns a generator which produces electricity.
  4. The electricity goes to the transformers to produce the correct voltage using step-up transformers.
  5. Step-down transformers are used to reduce the voltage to safe levels so we can use it in our homes.
37
Q

what happens when a current flows through a wire

A

some energy is lost as heat.

38
Q

what happens with a higher current

A

The higher the current, the more heat is lost.

39
Q

why does the National Grid transmit electricity at a low current, but high voltage.

A

To reduce energy losses in wires

40
Q

how does the national grid reduce energy losses in wires

A

the National Grid transmits electricity at a low current, but high voltage.

41
Q

what are renewable energy resources

A

energy sources that quickly replenish themselves and can be used again and again.

42
Q

what are some renewable energy sources

A

wind, geothermal, wave, tidal, solar, biomass, hydroelectric

43
Q

what are some advantages of renewable energy resources

A

will not run out, solar panels cheap to maintain, unused energy produced by households can be sold back to the national grid, renewable energy technologies could produce more jobs, fewer greenhouse gas emissions, stable source of energy - cost doesn’t change much, can be used on small or large scales

44
Q

what are some disadvantages of renewable energy resources

A

hydroelectric systems can harm environments, wind turbines can be noisy and can only be used when weather is suitable, not all places in world can use them, technology expensive to buy, energy produced at slower rate, lot of land required.

45
Q

what unit is used for energy

A

joules (J) or kilojoules

46
Q

what unit for energy do energy suppliers use

A

kilowatt hour (kWh)

47
Q

what does the power rating of an electrical appliance tell you

A

how fast that something transfers energy.

48
Q

how much is 1kW in watts

A

1000W

49
Q

how do you calculate the Energy an Appliance

Transfers

A

Energy Transferred (j) = Power (W) x Time (s)

50
Q

how do you calculate the Energy an Appliance

Transfers in kilowatt hours

A 
Energy Transferred (kWh) = Power (kW) x Time 
(h)
51
Q

how do you calculate The cost of electricity

A

cost = power (kW) × time (hour) × cost of 1 kWh (pence)

52
Q

How do we save energy in our homes?

A

Switch off appliances when not in use. Use more efficient appliances. insulate rooms

Science Y9 (7 decks)

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