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35 Cards in this Set
- Front
- Back
Kinetic energy |
1/2 x m x v x v |
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Spring constant |
Force | extension |
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Extension |
Stretched - unstreached |
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Elastic potential |
0.5 x k x e x e |
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Gravitational energy |
Ep = m x g x h |
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Specific heat capacity |
AE = m x c x AO |
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Work done is affected by |
Size of force and distance travelled |
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Work done |
Force x Distance |
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Power |
Work done | time taken |
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Conservation of energy |
Total amount of energy present stays the same as the amount before and after any changes |
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Energy transfers |
Energy can be transferred, stored and dissipated |
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How to reduce unwanted energy transfers |
Lubrication, tightening loose parts and thermal insulation |
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Efficiency |
How good something is at transferring one energy into another useful form |
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Electrical appliances |
Transfer electrical energy into another form eg, fan |
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Efficiency equation |
Useful output energy transfer / total input energy transfer |
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Percentage efficiency |
Efficiency X 100 |
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Renewable energy |
Wind Water Biofuel Geothermal Solar |
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Non renewable energy |
Wood Co Oil Nuclear Natural gas |
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3 main uses of energy |
Transport Electricity generation Heating |
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Electrical charge and current |
Charge = current (a) X time (s) |
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Electrical current is the rate of flow of charge |
Current = charge / time |
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Electrical circuit |
If you break the circuit any where everything will stop |
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Resistors |
Specially designed to provide resistance can speed up of low or slow down if high the current flow |
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Resistance |
Voltage / current Measures in ohms |
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Ohms law |
The current through a metallic conductor is directly proportional to the potential difference across its ends where the temperature and other conditions are constant ( current and voltage are directly proportional )
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Metallic conductors (ohms law) |
Directly proportional Straight line |
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Filament lamp |
Not directly proportional S shape through graph As filament heats the resistance increases |
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Diode |
Allows electrical current to pass in one direction. Whilst being blocked from travelling the other way ( anode-cathode) ——/ - that shape through graph |
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Thermistors |
A resistor that responds to changes in temp Hotter more current flows Electrons break from bond and become free to take part in conduction Eg. Temp rises Resistance goes down Total resistance goes down Greater current flow Lamp gets brighter |
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LDR |
Resistor that responds to light intensity Light intensity increases and more free electrons are created, resistance increases Eg. Light increases LDR resistance goes down Total resistance drops Greater current flow Louder bizz |
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Finding resistance of a number of resistors in a series |
Add the resistances off resistors together |
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Parallel circuits |
Circuits which have junctions whet the electrical pathway divides/branches |
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Total current |
I total = I1 +I2 +I3 |
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Voltage in a parallel circuit |
Voltage is the same everywhere |
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Total resistance in a parallel circuit |
R total = V/I |