Energy, Work and Power Flashcards
What type of energy is stored in a moving object?
Kinetic Energy
What happens, in terms of energy, when an object is lifted?
It gravitational potential energy increases
Give an equation for kinetic energy
KE = ½mv²
Give an equation for gravitational potential energy
GPE = mgh
When work is done against friction or resistance, what happens
There is less of a change in kinetic energy because some energy is dissipated through heating
What is the original source of most of the energy on Earth?
The sun
What forms of energy do not ultimately
come from the sun?
- Geothermal
- Nuclear
- Tidal
What is the source of the sun’s energy?
Nuclear fusion
What are the main energy resources
available to humans?
Fossil fuels (coal, gas and oils), nuclear fuels, biofuels, wind, hydroelectricity, tides, and solar energy
Define renewable energy
Energy from a source which does not run out, so can be replenished
Which energy sources are renewable
- biofuels
- wind
- hydroelectricity and tidal power
- geothermal
- solar power
Which energy sources are non-renewable
- fossil fuels
- nuclear fuel
Why is non-renewable energy used to
provide electricity on a large scale?
Non-renewable sources tend to have a larger energy output per kilogram of fuel
What is efficiency
The ration of uselful work done to energy supplied
Equation for efficiency
Efficiency =Useful energy output / Total energy input
How can efficiency be increased
- Reducing waste output (by lubrication, thermal insulation)
- Recycling waste output (recycling
thermal waste energy as input energy)
Define work done
- work is done on an object when energy is transferred
- equal to the product of force and distance
Give the equation for work done
W = Fd
Define power
Power is the rate at which enrgy is transferred, or the rate at which work is done
Give an equation for power
power (W) = energy (J) ÷ time (s)
power (W) = work done (J) ÷ time (s)
