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Physics > Energy > Flashcards

Energy Flashcards

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1
Q

What is energy?

A

Energy is responsible for things happening, and it can be stored in a variety of energy stores

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2
Q

How can energy be transferred?

A

Energy can be transferred through -

  • heating
  • waves
  • electric current
  • force
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3
Q

Can energy be created or destroyed?

A

No, energy cannot be created or destroyed, although it can be transferred

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4
Q

What is energy measured in?

A

Joules

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5
Q

Some energy stores are…

A 
Elastic potential
Chemical potential
Gravitational potential
Nuclear
Internal
Magnetic
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6
Q

Some energy transfers are…

A 
Mechanical energy
Light energy
Sound energy
Thermal energy 
Kinetic energy
Electrical energy
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7
Q

What is work done?

A

Work done is when a force causes a body to move, so work is done on the body

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8
Q

What is the equation for work done?

A

Work done = Force x Distance moved in direction of force

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9
Q

What is the symbol equation for work done?

A

WD = FD

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10
Q

Note on work done…

A

One joule is the work done when a force of 1 Newton moves through a distance of 1 metre

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11
Q

Work done example…

A

If you have to exert an UPWARD FORCE of 10N in order to raise a book through a vertical distance of 1.5M, the work dome is 15J - this is also the amount of energy transferred

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12
Q

What is the formula for kinetic energy?

A

KE = 1/2MV^2

Kinetic Energy = 1/2 x Mass x Speed^2

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13
Q

What is the formula of Gravitational Potential Energy?

A

GPE = Mass x Gravitational field strength x (delta) Height

(Delta)GPE = MG(delta)H

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14
Q

What is important to consider when comparing fuels?

A

Energy Density

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15
Q

What is Power?

A

POWER is ENERGY TRANSFERRED per unit of TIME

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16
Q

What is the equation (Word and Symbol for Power)?

A

Power = Energy Transferred / Time

P = E / T

P = WD / T

17
Q

What is the equation for Efficiency?

A

Efficiency = Useful energy transferred by the device / Total Energy

18
Q

What are some reasons for devices wasting energy?

A

Devices waste energy through friction, resistance, air resistance and sound.

19
Q

How can someone reduce energy wasted?

A

Lubricate moving parts, Use wires with little electrical resistance, streamline shapes to counter air resistance, cut out noise by reducing vibration

20
Q

What is a renewable energy resource?

A

One that is replenished as it is used

21
Q

What are some uses of energy resources?

A

Transport, electrical energy use in homes, thermal use for heating

22
Q

What is the equation for elastic potential energy?

A

Ep = 1/2ke^2

23
Q

What is the unit for a spring constant?

A

N/m

24
Q

Why might motors have a high kinetic energy?

A

Because it has a high power

25
Q

What is a biofuel?

A

A renewable, carbon neutral fuel obtained from a living or recently living organism

26
Q

How does a wind turbine work?

A
  • Wind passes over turbine blades
  • Making the turbines rotate
  • Which drives a generator
  • Producing electricity
27
Q

How does a wave generator work?

A
  • Waves rock a floating turbine
  • Moving turbine up and down
  • Generating electricity
28
Q

How is geothermal energy harvested?

A
  • Comes from energy released deep from within Earth
  • Energy heats up surrounding rocks
  • Deep holes are drilled and water is pumped down
  • Water comes back to surface as steam
  • Which is used to drive turbines
29
Q

How do solar cells work?

A
  • Transfers energy through EM radiation from Sun
  • Straight into electricity
  • So very useful to power small devices
  • Such as watches
30
Q

Renewable Energy resources advantages

A
  • Wil never run out

- Do not cause environmental harm

31
Q

Renewable Energy resources disadvantages

A
  • Cannot currently meet world energy demand

- Unreliable

32
Q

What is the specific heat capacity?

A

The energy required to heat 1kg of a substance by 1°C

33
Q

How can we reduce energy wasted in houses?

A
  • Fibreglass loft insulation reduces rate of energy transfer through the roof
  • Cavity wall insulation reduces rate of energy transfer through walls
  • Aluminium foil behind radiators reflects radiation back into the room
  • Double glazed windows reduces rate of energy transfer through windows
  • Thick, low conductivity bricks reduces rate of energy transfer through outer walls
34
Q

Advantages of Nuclear Power

A
  • Do not produce greenhouse gases

- Transfer much more energy per kilogram than fossil fuels

35
Q

Disadvantages of Nuclear Power

A
  • Radioactive waste is a biproduct that must be stored fore years
  • Accidents can happen putting lives at risk
36
Q

Equation for Efficiency?

A

Useful output energy transfer / Total input energy transfer

Physics (19 decks)

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