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Physics > CP3- Conservation Of Energy > Flashcards

CP3- Conservation Of Energy Flashcards

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1
Q

name the 8 energy stores.

A
  • kinetic- moving
  • thermal- heat
  • chemical- things that can release energy by a chemical reaction
  • gravitational potential- in a gravitational field and can fall
  • elastic potential- stretched
  • electrostatic- two charges that attract or repel
  • magnetic- two magnets that attract or repel
  • nuclear- energy stores inside atoms
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2
Q

what is kinetic energy?

A
  • energy stored in moving objects
  • the amount of kinetic energy stored in a moving object depends on mass and speed
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3
Q

what is the equation for kinetic energy?

A

kinetic energy= 1/2 x mass x speed^2

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4
Q

what is gravitational potential energy?

A
  • energy that is stored due to an object being at a height above the earths surface
  • the amount of GPE depends on the mass, the strength of gravity and the distance above surface
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5
Q

how do you calculate GPE?

A

GPE= mass x gravitational field strength x change in vertical height

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6
Q

what is the law of conservation of energy?

A

energy cannot be created nor destroyed, it can only be transferred from one store to another. this involves useful energy aswell as wasted energy

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7
Q

what is efficiency?

A

the amount of energy that is transferred, not involving wasted energy

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8
Q

what does dissipated mean?

A

transferred to surroundings

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9
Q

how can you reduce friction to reduce wasted energy by heating

A

substances that can lubricate like oil or gases

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10
Q

describe an example of energy transfers on a motor lifting a load.

A
  • energy is transferred electrically from the main
  • kinetic energy from the motor is transferred to the kinetic energy and GPE stores of the load
  • some of the wasted energy includes the energy transferred mechanically to the thermal energy stores, generating heat
  • also the energy transferred electrically to the thermal energy of the circuits
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11
Q

how do you calculate efficiency?

A

useful energy transferred by device / total energy supplied to device

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12
Q

how does lubrication reduce wasted energy?

A
  • reduces energy transferred by friction, reducing the amount of energy in the thermal store and therefore reducing how much heat is dissipated
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13
Q

how does insulation reduce wasted energy?

A
  • reduces the amount of energy transferred by heating
  • reduces conduction so energy transfers slower across materials and can be preserved
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14
Q

how is energy transferred by heating in conductors?

A
  • vibrations are passed between particles in a solid
  • metals are good conductors
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15
Q

what is thermal conductivity?

A

how well a material transfers energy by when heated

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16
Q

how is energy transferred by heating in convection?

A

fluids that are warm rise and create a convection currents

17
Q

how do you decrease the rate of energy transfer by heating in a material?

A
  • increase thickness
  • decrease thermal conductivity
18
Q

what are non renewable energy resources?

A
  • will run out one day
  • fossil fuels and nuclear fuels
19
Q

positive of non renewable energy.

A
  • reliable since there is still a lot for current demand
  • low costs to build and run fossil fuel
20
Q

negatives of non renewable energy.

A
  • nuclear power plants are costly and difficult to safely decommission
  • fossil fuels are running out
  • co2 emissions enhance the greenhouse effect, contributing to global warming
  • coal and oil burning can release sulphur dioxide causing acid rain
  • oil spillages can damage the environment
  • nuclear waste is very difficult to dispose of
21
Q

what are renewable energy resources?

A
  • will never run out
  • biofuels, hydroelectric power, wind power, solar power, tides
22
Q

positives of renewable energy.

A
  • do not cause pollution or emit carbon dioxide
23
Q

negatives of renewable energy.

A
  • cannot be the primary resource since its not always available
  • don’t provide enough energy
  • getting them to operate in the first place may need to utilise fossil fuels and non renewable power sources so it is counterproductive
24
Q

what are biofuels?

A
  • renewable energy created from animals waste or plants
  • they are carbon neutral since they emit the same amount of carbon they absorbed from the atmostphere
  • however energy will be needed to grow and harvest the crops so its not fully carbon neutral
25
Q

what are solar cells?

A
  • converts solar energy directly into electrical energy
  • not available all the time
  • use a lot of energy to make
  • generates electricity on a small scale
26
Q

what is hydroelectric power?

A
  • electricity generated by water falling in places
  • can be generated in dams and reservoirs
  • building dams can have environmental effects, destroying habitats and flooding other areas
  • may not always be available since reservoirs could dry up
  • can immediately respond to electricity demands
27
Q

what are wind turbines?

A
  • generate electricity with wind
  • however LOTS are needed in order to produce the same amount as a fossil fuel power station
  • initial costs are high but running costs are minimal
  • some people think they spoil the landscape
  • only work when windy
28
Q

what is tidal power?

A
  • generating electricity through turbines in a dam turn as tides flow in and out
  • not available at all times
  • can damage underwater habitats
29
Q

How does insulation reduce the rate of energy transfer by heating?

A
  • if one side of an object is heated, the particles will vibrate and collide with particles from the colder side of the object, therefore transferring energy from kinetic stores (this is called conduction when energy is transferred through an object)
  • since all materials have thermal conductivity (how easily they transfer energy by conduction), the lower this thermal conductivity, the slower the rate of energy transfer, therefore meaning that an object or building will cool more slowly
  • houses can also create cavity walls where there is a gap between the inner and outer wall so that less conduction occurs, air has very low thermal conductivity
  • thicker walls also slow the rate of energy transfer

Physics (13 decks)

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