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Energy Transfer
Diagrams show energy input, and the energy output, And the forms that the energy takes, such as the waste output energy. Motors also waste energy as heat
Energy changes - object projected upwards
KE transferred to GPE, then vice-versa as it falls back down
Energy changes - Object projected up a slope
KE transferred to GPE (and also to heat if friction is present)
Energy changes - moving object hitting an obstacle
KE transferred to sound/ KE transferred to obstacle if that moves too
Energy changes - object being accelerated by a constant force
Object is having work done to it, with it gaining KE. Whatever supplies the force is having its energy is transferred to KE
Energy changes - vehicle slowing down
KE transferred to heat (through brakes)
Energy changes - boiling water in kettle
Electrical energy to thermal
Conservation of energy means that the…
total energy of an isolated system remains constant
A ‘closed system’ has no…
external forces acting on it
Waste energy forms
Light, sound, and (most commonly) heat
Ways to reduce waste
Lubricate systems so less friction and less heat created and thermal insulation so less heat is lost to surroundings
Reduced waste energy in buildings
thicker walls means greater thermal insulation so less heat is lost, and air cavities between walls causes lots of heat loss by convection - cavity wall insulation fills in this gap and prevents air flow
Efficiency equation
Useful energy transferred by the device/ total energy supplied to the device
Efficiency can be increases by….
reducing or recycling waste output
Energy sources
Fossil fuels, Nuclear fuel, Bio-fuel, Wind, Hydro-electricity, Tidal, Solar
Non-renewable energy is used…
for large-scale energy supplies due to the large energy output per kg of fuel - renewable resources can’t provide such a large amount of energy as easily
Renewable energy has become more important due to the…
finite lifetime of fossil fuels, and so their development has become more important
During industrial revolution, fossil fuels became…
an important source of energy as it was easy to mine and provided lots of energy
