Physics - Energy

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A system
A system is an object or group of objects.
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Types of energy stores
magnetic, internal (thermal), chemical, kinetic, electrostatic, elastic potential, gravitational potential, nuclear
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Closed system
Neither matter nor energy can enter/leave. The net change in the total energy of a closed system is ALWAYS ZERO
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How is energy transferred?
Energy is transferred by stores. When energy is transferred to an object, the energy is stored in one of the object's energy stores.
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Formula for Work Done
W = Fd OR Work Done (J) = Force (N) x Distance (m)
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What does Kinetic Energy depend on?
KE depends on an object mass and speed. The greater the mass and the faster it's going, the more energy there will be
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Formula for Kinetic energy
KE = 1/2 mv OR Kinetic energy (J) = 1/2 x mass (kg) x speed (m/s)
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What does Gravitational Potential Energy depend on?
GPE depends on object's mass, height and grav. field strength. The HIGHER the object is lifted, the more energy is transferred to this store.
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Formula for Gravitational Potential Energy
GPE = mgh OR Gravitational Potential Energy (J) = mass (kg) x grav. field strength (N/kg) x height (m)
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Formula for Elastic Potential Energy
Ee = 1/2 ke OR Elastic Potential Energy (J) = 1/2 x Spring Constant (N/m) x Extension (m)
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What is Specific Heat Capacity?
The amount of energy required to change the temperature of 1kg of a substance by 1°C
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Formula for Specific Heat Capacity
E=mcΔT OR Energy (J) = mass(kg) x Specific Heat Capacity(J/kg°C)
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What is Power?
The rate of energy transfer/rate of doing work
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What unit is Power measured in?
Watts (W)
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What is one Watt equal to?
One Watt = One Joule transferred per second OR W = J/s
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Formula for Power
P = E/t OR P = W/t OR Power (W) = Energy Transferred (J) ÷ time (s)
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What is the Conservation of Energy?
Energy can be transferred usefully, stored or dissipated, but can NEVER be CREATED or DESTROYED
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Formula for Efficiency
Useful output energy transfer/Total input energy transfer OR Efficiency = Useful Power output /Total power input
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Methods to reduce unwanted Energy Transfers
Lubrication and Insulation
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Non-Renewable Energy Resources will...
...RUN OUT one day
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What are non-renewable energy sources?
They are fossil fuels and nuclear fuel (e.g. uranium and plutonium)
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What are the three main fossil fuels?
Coal, Oil, Natural gas
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Renewable Energy Resources will...
...NEVER Run Out
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Examples of Renewable energy sources
The Sun (Solar), Wind, Water waves, Hydro-electricity, Bio-fuel, Tides, Geothermal
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Other cards in this set

Card 2

Front

Types of energy stores

Back

magnetic, internal (thermal), chemical, kinetic, electrostatic, elastic potential, gravitational potential, nuclear

Card 3

Front

Closed system

Back

Preview of the front of card 3

Card 4

Front

How is energy transferred?

Back

Preview of the front of card 4

Card 5

Front

Formula for Work Done

Back

Preview of the front of card 5
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