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Physics > topic 1 - energy > Flashcards

topic 1 - energy Flashcards

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1
Q

What is a system?

A

an object or group of objects

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2
Q

what happens when a system changes?

A

the way the energy is stored changes when a system changes

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3
Q

what are the 8 energy stores? Give examples for each

A

magnetic - fridge magnets
internal (thermal) - human bodies, hot coffees
chemical - food, muscles, electrical batteries
kinetic - moving objects
electrostatic - thunderclouds
elastic potential - inflated balloons, stretched hairbands
gravitational potential - the energy of an object at height
nuclear - the energy stored in the nucleus of an atom

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4
Q

How does heating change the energy stored within a system?

A
  • increases the energy of the particles
  • this either raises the system’s temperature or, produces a change of state (e.g. solid to liquid)
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5
Q

How is work done to change the energy stored within a system?

A
  • work is done when energy is transferred from one store to another
  • when a force causes an object to move, work is done against frictional forces, causing the object’s temperature to increase and energy is lost as heat and sound to the surroundings
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6
Q

What is the relationship between work done when a current flows in a circuit?

A
  • a current flows when there is a potential difference applied to the circuit
  • this gives each charge an amount of energy
  • this is the work done by the power supply when a current flows
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7
Q

what is specific heat capacity?

A

the amount of energy required to raise the temperature of a 1kg substance by 1°C

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8
Q

what is power?

A

the rate at which energy is transferred or the rate at which work is done

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9
Q

What is the law of energy conservation?

A

energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed

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10
Q

state any changes in the total energy of a ball that is kicked, assuming that no external forces act.

A

the total energy of the system remains constant due to the conservation of energy

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11
Q

what is waste energy?

A

the energy that is not used by the device for its desired purpose

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12
Q

What energy changes occur in a filament light-bulb?

A
  • electrical energy is transferred into light and heat energy
  • light is a useful energy form, heat is a waste energy
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13
Q

how can the efficiency of a system be increased?

A
  • reducing waste output (by lubrication, thermal insulation etc
  • recycling waste output (eg. recycling thermal waste energy as input energy)
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14
Q

Why can lubricating a bike’s gears allow the bike to go faster?

A
  • adding a lubricant reduces friction
  • so less work is done against friction
  • so less energy is wasted as less is transferred to the surroundings as heat
  • and the useful kinetic energy stored can remain higher
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15
Q

What is the consequence for energy transfer of a material with a high thermal conductivity?

A

the rate of energy transfer through the material is higher than for a material with a lower thermal conductivity

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16
Q

What is conduction?

A

the process where vibrating particles transfer energy to neighbouring particles

17
Q

What is the singe device used to measure energy?

A

Joulemeter

18
Q

What is the device used to measure current?

A

ammeter

19
Q

what is the device used to measure the potential difference?

A

voltmeter

20
Q

What is convection?

A

convection is where energetic particles move away from hotter to cooler regions

21
Q

What happens to the density of air as it gets warmer?

A

the density decreased (so hot air will rise)

22
Q

Why should the material used for house insulation have a low thermal conductivity?

A
  • the higher the thermal conductivity the higher the rate of energy transfer by the material
  • so a low thermal conductivity would transfer energy with a low rate and keep the energy in the house for longer
23
Q

What are three methods of reducing heat loss in a building?

A
  • double glazing
  • loft and wall insulation
  • thicker walls
24
Q

How can the efficiency of a mechanical machine with moving parts be improved?

A

lubricate any moving parts to reduce the friction and therefore energy loss due to heating

25
Q

How can the efficiency of a radiator be improved?

A

installing metal foil sheets behind the radiator to reflect the heat back into the room rather than it being absorbed into the walls

26
Q

How can the efficiency of boiling water in a pan be improved?

A

by placing a lid on the pan to reduce the heat loss from the top

27
Q

what is a renewable energy resource?

A

an energy source which can be replenished as it is being used up

28
Q

what are seven examples of renewable energy resources?

A
  • the sun
  • the wind
  • water
  • hydroelectricity
  • bio-fuel
  • tides
  • geothermal
29
Q

What are four non-renewable energy resources?

A
  • coal
  • oil
  • gas
  • nuclear fuel
30
Q

What are the two advantages of wind power?

A
  • no pollution
  • renewable energy
31
Q

What are the disadvantages of wind power?

A
  • spoils the view
  • very noisy
  • unreliable
  • cannot increase supply when there is extra demand
32
Q

What are the two advantages of solar energy?

A
  • no pollution
  • renewable energy
33
Q

What are the two disadvantages of solar energy?

A
  • only reliable in day time
  • initial costs are high
34
Q

What is geothermal power?

A

energy in underground thermal energy stores caused by the decay of radioactive elements

35
Q

What are biofuels made from?

A

plants and animal dung

36
Q

What are the advantages of fossil fuel power plants?

A
  • they are reliable
  • they can meet current demand
37
Q

What are the disadvantages of fossil fuel power plants?

A
  • non renewable so they are runnng out, release carbon dioxide when burned out which contributes to the greenhouse effect and global warming
38
Q

What is a disadvantage of nuclear power?

A

dangerous and difficult to dispose of

Physics (8 decks)

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