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27 Cards in this Set
- Front
- Back
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Chemical Energy Stores |
Fuels Food Batteries |
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Kinetic Energy Stores |
The energy an object has while its moving The energy depends on its mass and it’s speed. Greater mass and speed = greater KE store |
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Gravitational Potential Energy |
Describes the energy an object has depending on its position relative to the ground or its position in the Earth’s gravitational field. GPE increases when an object moves upwards |
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Elastic Potential Energy |
Describe the energy an object has when it is being stretched or squashed. Object is an elastic if it regains it’s normal shape. When it is at its regular shape the energy becomes available for other transfers. |
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Thermal Energy |
Describe the energy an object has because of its temperature |
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The Principle of the Conservation of energy |
The Principle that energy can be transferred usefully, stored or dissipated but cannot be created or destroyed. |
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Microwave - what energy stores |
Electric => Heat |
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Electric Fan |
Electric => Kinetic |
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System |
Just an object or group of objects |
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Closed System |
An object or group of objects in which no energy transfers take place out or in |
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Can energy be transferred within the closed system? |
Yes, energy can be transferred to different stores e.g: - when an object falls, the gpe decreases and the kinetic energy increases - when a person stretches an elastic band, the chemical energy store of the muscles decreases and the epe store of there elastic band increases |
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Pendulum |
GPE decreases when swinging and kinetic energy Eventually stops as energy is dissipated and friction in the air |
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Work Done |
When a force moves an object energy is transferred and work is done Energy supplied = work done in the moving object No movement = No work done on object |
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Work Done = Force x _________ W = F x _______ |
Work Done = Force x Distance W = F x s Joules = Newtons x Metres |
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Friction |
The force that opposes the motion of two surfaces in contact with each other Work done to overcome friction is mainly transferred to thermal energy stores by heating |
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GPE=Mass x gfs x ____________ ΔE = m x g x _________ |
change in GPE=Mass x gfs x change in height ΔE = m x g x Δh Gfs on earth is 9.8 N/kg |
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Kinetic Energy = 1/2 x mass x___ Ek = 1/2 x m x _______ |
Kinetic Energy= 1/2 x mass x velocity^2 Ek = 1/2 x m x v^2 Joules = Kg x m/s |
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EPE=1/2 x spring constant x____ EPE=1/2 x k x ___________ |
EPE = 1/2 x spring constant x extension^2 EPE = 1/2 x k x e^2 Joules = 1/2 x spring constant x extension^2 |
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Useful Energy |
Energy transferred to where it is wanted in the form that is wanted |
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Wasted Energy |
Energy that is not useful and transferred into an undesired pathway Usually transferred as sound or heat energy. Energy is dissipated into the surroundings. |
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Input energy |
The energy supplied to a machine/device |
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Output energy |
Total output energy = input energy Can be both useful and wasted |
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Efficiency |
How useful a machine/device is. Less energy wasted then more useful and efficient device is. |
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Efficiency = (useful energy / ___) x 100 |
Efficiency = (useful energy / total input energy) x 100 |
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How can you increase efficiency |
- Lubrication is used to reduce friction between moving parts - Aerodynamic shape to reduce air resistance - Copper wires to reduce electrical resistance |
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Power |
Rate at which an appliance transfers energy |
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Power=Energy Transferred /____ P = E/______ |
Power=Energy Transferred / time taken for transfer P = E / t Watts = Joules / seconds |
