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28 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Labelled Sankey Diagram |
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Work Done=Energy Transferred |
Forces can cause work to be done, but only when they make an object move |
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Work Done=Force Applied x Distance (moved along the line of action by a force) |
W=Fs |
W=Work done, measured in joules (J) F=Force applied, measured in Newtons (N) s=Distance moved, measured in metres (m) |
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1J of work is done when a force of 1N causes a displacement of 1m |
1 Joule=1 Newton-Metre |
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Work done against the frictional forces acting on an object causes a rise in the temperature of an object |
Examples: Rubbing hands together Brake pads and wheel disks Meteorites entering Earth’s atmosphere |
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Gravitational potential energy is energy stored due to an object’s position in a gravitational field |
Ep=mgh |
Ep=Gravitational potential energy, measured in joules (J) m=Mass, measured in kilograms (kg) g=Gravitational field strength, measured in Newtons per kilogram (N/kg) h=Vertical distance moved, measured in metres (m) |
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Elastic potential energy |
The energy that is stored in an object that is being stretched |
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Calculate energy stored in a stretched spring |
Ee=1/2Ke^2 |
Ee=Elastic potential energy, measured in joules (J) K=The spring constant, measured in Newtons per metre (N/m) e=Extension, measured in metres (m) |
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All moving objects have stores of... |
Kinetic energy |
Vehicles like cars transfer this kinetic energy from the fuel that they burn |
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Equation for kinetic energy |
Ek=1/2mv^2 |
Ek=Kinetic energy, measured in Joules (J) m=Mass, measured in kilograms (kg) v=Velocity, measured in metres per second (m/s) |
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Conversions 1km=... 1 mile=... 1cm=... 1mm=... 1 minute=... 1 hour=... 1 year=... |
1,000m 1,600m 0.01m 0.001m 60 secs 60 minutes=3,600 secs 365.25 days |
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How fast is this ball travelling just before it hits the ground? |
Ep=Ek mgh=1/2mv^2 gh=1/2v^2 SqR of 2gh=v SqR of 2x9.8x1.5=v v=5.42m/s |
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Power |
The rate at which energy is transferred or the rate at which work is done |
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Power Equation |
P=E/t |
P=Power, measured in Watts (W) E=Energy transferred, measured in Joules (J) t=Time, measured in seconds (secs) |
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Specific Heat Capacity (SHC) |
A measure of how much energy is required to raise the temperature of 1kg of a substance by 1 degrees c |
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SHC Calculation |
^E=mc^0 |
^E=Change in energy, measured in Joules (J) m=Mass, measured in kilograms (kg) c=SHC, measured in Joules per kilogram degree Celsius ^0=Change in temperature, measured in degree Celsius |
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SHC of substances |
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SHC of water facts |
Water has a very high SHC. It needs more energy to heat it up than other substances. It stores more energy when it is hot, and so gives out more energy when it cools down. This is why a hot water bottle is effective in warming a bed. Water is a good substance to transfer energy around a central heating system. It is also good for cooling down engines in cars. The SHC of water also affects our weather. Islands surrounded by water tend to stay at the same temperature, while large areas of land get very hot in summer and very cold in winter. |
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Efficiency |
A measure of how well a machine fulfils its purpose or a measure of the useful energy transferred in relation to the total amount supplied |
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Efficiency equation |
Efficiency=Useful energy transfer/Total input energy transfer |
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Energy efficiency of common items |
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Thermal energy always... |
flows from areas of high concentration to areas of low concentration- until all areas are the same concentration |
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Conduction |
Thermal energy transfer in a solid. Transfers energy through particle vibrations |
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Why and how do metals conduct electricity? |
They have free delocalised electrons. The delocalised electrons knock into particles and transfer some of their kinetic energy (motion energy) to the particle that they hit. This means that heat energy can travel much more quickly by this method. |
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Convection |
Transfers energy through particle collisions. Like solids, when a liquid or gas (a fluid) is heated it expands slightly. The particles spread out and the fluid becomes less dense. The hot less dense fluid will float up. When heat leaves substances, the molecules vibrate more slowly. The atoms can get closer which results in the matter contracting and becoming more dense. The dense cold fluid will sink. |
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Infared Radiation |
Thermal energy transfer through electromagnetic waves |
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Conduction and convection both require... |
a medium to pass through- if there are no particles this cannot happen |
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Infared radiation does not require... |
a medium to pass through- it is how the Sun's thermal energy reaches us |
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