P1 - Energy

Question 1

Kinetic Energy

Answer 1

Energy stored in a moving object
Kinetic energy = ½ x mass x velocity²
Ek = ½mv²

Question 2

Elastic Potential Energy

Answer 2

Energy stored in a spring when it’s stretched
Elastic potential energy = ½ x spring constant x extension²
Ee = ½ke²

Question 3

Gravitational Potential Energy

Answer 3

Energy stored in a raised object
Gravitational Potential Energy = mass x gravitational field strength x height
Ep = mgh

Question 4

Specific Heat Capacity

Answer 4

Energy required to raise the temperature of 1kg of a substance by 1°C
Energy = mass x specific heat capacity x temperature change
E = mcΔT

Question 5

Power

Answer 5

Rate at which energy is transferred or the rate at which work is done
Power = energy transferred ÷ time
P = E ÷ t
Power = work done ÷ time
P = W ÷ t

Question 6

Energy Transfers

Answer 6

Energy can be neither created nor destroyed, only moved between stores - this is known as an energy transfer. In all systems changes energy is dissipated, meaning it is stored in less useful ways - this energy is often described as being wasted

Question 7

Efficiency

Answer 7

The ratio of useful work done by a machine/device to the energy supplied to it
Efficiency = useful energy output ÷ total energy input
Efficiency = useful power output ÷ total power input

Question 8

Increasing Efficiency

Answer 8

Reducing wasted energy:
- lubrication (reduces friction so less energy is lost as heat)
- thermal insulation (less useful thermal energy lost)
Recycling waste output:
- absorbing thermal waste and reusing as input energy

Question 9

Renewable Energy

Answer 9

Energy which can be replenished as it is used, e.g:
- wind
- solar
- tidal
- wave
- biofuel
- geothermal
- hydro-electricity
It tends to have a lower energy output per kilogram of fuel, and isn’t always reliable

Question 10

Non-Renewable Energy

Answer 10

Energy which is finite, or cannot be replenished as quickly as it is being used, e.g:
- fossil fuels (coal, oil, gas)
- nuclear fuel
It tends to have a greater energy output per kilogram of fuel than renewable energy

Question 11

Environmental Impact of Fossil Fuels

Answer 11

Extracting fossil fuels involves destroying landscapes and when combusted, they release harmful emissions such as CO2