Physics Flashcards
Energy
The ability to do work. Measured in Joules (J)
Energy Store
How energy is kept by an object until it is ready to be used
Energy Transfer
How energy is moved from one object or place to another
Conservation of energy
Energy cannot be created nor destroyed. Only moved from one store to another
Dissipate
When energy is transferred to the thermal store of its surroundings, we say that it has dissipated
Power
The rate at which energy is transferred P=E/T
Watt (W)
Unit of Power
Efficiency
The more energy something wastes the less efficient it is
Sankey diagram
A diagram that shows the efficiency of a machine
What are the 8 energy stores
Magnetic, Kinetic, Thermal, Gravitational potential, Electrostatic, Chemical, Elastic Potential, Nuclear
Describe the energy transfer that occurs as a ball falls to the ground
Gravitational potential - Kinetic
Where does energy end up at the end of most energy transfers?
In the Thermal Store of the surroundings
How do you convert KW into W?
Multiply by 1000
How do you convert W into KW?
Divide by 1000
What is the formula for efficiency
Useful energy out ÷ Total energy in
or
useful power out ÷ Total power in
Give the equation for finding Kinetic Energy
Ek = 0.5 x m x v2
Give the equation for finding gravitational potential energy
Ep = m x g h
Spring Constant
It measures how difficult it is to compress or stretch a spring. The larger the number, the harder it is to compress a spring
Specific Heat Capacity
How much energy is needed to heat up 1kg of a material by a temperature of 1’c
Thermal conductivity
Tells how well a material conducts heat. The higher the thermal conductivity of a material the higher the rate of energy transfer
Renewable energy source
The source of energy cannot be used up or can be replenished
Non-renewable energy source
It is finite - will eventually run out
National grid
A network of cables and transformers to distribute electricity to homes schools business and hospitals
What is the formula for Elastic Potential energy
Ee = 1/2 x k x e2
Where k is the spring constant measured in Newtons per metre
Give the equations for specific heat capacity
▲E= m x c ▲
Give four ways to prevent unwanted energy transfers in a home
Cavity walls, Loft insulation, Double glazed windows, draught excluders
Name 4 non renewable energy sources
Coal, oil, gas and nuclear
Name 7 renewable energy sources
Solar, Wind, Wave, Tidal Wave, Hydroelectric, Biofuel, Geothermal,
Give two disadvantages of burning fossil fuels
Burning fossil fuels releases carbon dioxide (causes global warming) and sulphur dioxide (acid rain)
What are trnasformers
Step up transformers increase the potential difference in the cables
Step down transormers decrease the potential difference in cables
