Term
| Forms of Energy (nine of them in IGCSE |
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Definition
| Kinetic, Gravitational PE, Elastic PE, Thermal (heat), Light, Electrical, Sound, Kinetic, Chemical, Nuclear |
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Definition
| Energy is never created not destroyed, it just transfers from one form to another |
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| When energy converts from on form to another |
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| The fraction of useful work a machine does |
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Definition
Efficiency =
Useful energy output/ total energy input |
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Definition
| Energy flow diagram showing transfers in a system and its environment |
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Definition
| By conduction, convection or radiation |
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Definition
| Occurs chiefly in solids, by interaction between particles which transfers thermal energy |
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| Occurs in fluids. Warm fluid expands and is replaced by denser cooler fluid which sinks |
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| Does not require a medium. Energy is transferred by electromagnetic radiation travelling at the speed of light |
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| Materials which slow down the transfer of thermal energy |
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| A measure of energy transfer (in joules) |
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Definition
Work done = Force * distance travelled in direction of the force
W=Fd |
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Definition
| Unit of energy and work. 1 J = 1Nm |
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| Gravitational potential energy |
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Definition
| Energy an object has due to its position in a gravitational field |
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Definition
GPE = mass * g * height
GPE = mgh |
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Definition
| Energy which an elastic object has when it is stretched or squashed |
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Definition
| Energy which an object has due to its motion |
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Definition
KE = ½ * mass * speed2
KE = ½mv2 |
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Definition
The rate of doing work
or
the rate of transferring energy from one form to another |
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Definition
| Power = Work done/ time taken |
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Definition
The unit or power
1W = 1J/s |
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| These cannot be exhausted and are usually non-polluting eg solar, wind, wave, tidal, HEP, geothermal, biomass |
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| Once used up, these cannot be replaced eg oil, gas, coal, nuclear fuel |
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