# Physics units 1 - 4

Name at least 3 types of energy stores
Thermal energy, Kinetic energy, gravitational potential energy, elastic potential energy, chemical energy, electrostatic energy, nuclear energy
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what is work done?
work done is when energy is transferred, work can be done when current flows or by a force moving an object
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what happens to the energy of a falling object?
when an object is falling its gravitational potential energy is transferred to the kinetic energy store
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what is the kinetic energy equation?
kinetic energy = 1/2 x mass x velocity^2
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what is the gravitational potential energy equation?
gravitational potential energy = mass x gravitational field strength x height
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what is the elastic potential energy equation?
elastic potential energy = 1/2 x spring constant x extension^2
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what is specific heat capacity?
specific heat capacity is the amount of energy needed to raise the temperature of 1kg of a substance by 1 degree C
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equation involving specific heat capacity
change in thermal energy = mass x specific heat capacity x temperature change
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what is the conservation of energy principle?
energy can be transferred usefully, stored or dissipated, but can never be created or destroyed
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equation for power in terms of energy
power = energy transferred/time
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equation for power in terms of work done
power = work done/time
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what is conduction?
conduction is the process where vibrating particles transfer energy to neighbouring particles
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what is convection?
convection is where energetic particles move away from hotter to cooler regions
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how could you reduce unwanted energy transfers?
Lubrication - used to reduce the friction between an objects surfaces when it moves. Insulation - things such as cavity walls, loft insulation, double galzed windows and draught excluders prevent energy transfers due to conduction and convection
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efficiency in terms of energy
efficiency = useful output energy transfer/total input energy transfer
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efficiency in terms of power
effiecieny = useful power output/total power input
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what is non-renewable energy? give some examples
non-renewable energy sources will run out one day, they damage the enivronment but they provide most of our energy. some examples are coal, oil and natural gases
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what is renewable energy? give some examples
these will never run out but they do damge the environment, but not as badly as non-renewable sources, many of them are unreliable and do not produce that much energy. some examples are solar, wind, wave, hydroelectricity, bio-fuel, tidal, geothermal
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what is wind power?
wind turbines contain a gernerator which is rotated generating electricity. no pollution is created, but they stop working if wind speed is too high and cost quite a lot to set up initially
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what is solar power?
solar panels generate electric currents directly from sunlight. they generate a steady supply of power but only during the day and generate power only on a small scale
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what is geothermal power?
uses energy from underground thermal energy stores. however there aren't many suitable locations and the cost sometimes outways the amount of energy produced
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what is hydro-electric power?
transfers energy from the kinetic store of falling water. it can be used as an immediate response to increased demand but it has a big impact on the environment and it intially costs a lot
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what is wave power?
wave powered turbines turn a generator creating electricity. however they are fairly unreliable and not used on a large scale
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what is tidal power?
usually set up by placing a tidal barrage across a river and controlling the amount of water which flows through. reliable as tide happens twice a day and has the potential to produce a lots of energy
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what are bio-fuels?
bio-fuels are a renewable energy source which are fairly reliable and can be used to meet immidiate energy demands. however they cost a lot and destroy many natural habitats to be planted
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what are non-renewable energy sources?
non-renewable sources including fossil fuels and nuclear energy are reliable and are our many source of energy. however they are running out and cause environmental problems including increasing the greenhouse effect
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what is current?
current is the flow of electric charge. the greater the resistance across a component the smaller the flow of current
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equation for charge
charge = current x time
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equation for potential difference
potential difference = current x resistance
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what is an LDR?
an LDR is a light-dependent resistor, resistance falls in bright light and increases in the darkness
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what is a thermistor?
a thermistor is a temperature dependent resistor, in hot conditions resistance falls, in cooler conditions resistance increases
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what are some key features of series circuits?
everything is connected in a line and if one component stops then so does the circuit. cell potential difference adds up and total potential difference is shared. current is always the same, resistance adds up
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what are some key features of parallel circuits?
each component is seperately connected to the power supply an if one is discoonnected it does not affect the other at all. potential difference is the same across all components, current is shared between branches
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what are the two types of electricity supplies?
the mains supply is ac, battery supply is dc. ac is alternating current when current constantly changes direction, dc is direct current flows in the same direction.
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what are the three types of wires in most cables?
the neutral wire - blue - carries away current. the live wire - brown - provides the alternating potential difference. the earth wire - green and yellow - the safety wire stops the appliance from becoming live.
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equation for energy transferred
energy transferred = power x time
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other equation for energy transferred
energy transferred = charge flow x potential difference
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power dependent on current and potential difference
power = current x potential difference
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power without knowing potential difference
power = current^2 x resistance
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what is the national grid?
a giant network of wires which cover britain and distribute electricity around the country.
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what is static electricity?
build up of static is caused by friction. only electrons move during static electricity
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## Other cards in this set

### Card 2

#### Front

what is work done?

#### Back

work done is when energy is transferred, work can be done when current flows or by a force moving an object

### Card 3

#### Front

what happens to the energy of a falling object?

#### Back ### Card 4

#### Front

what is the kinetic energy equation?

#### Back ### Card 5

#### Front

what is the gravitational potential energy equation?

#### Back ## Comments

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