Energy Flashcards
Chemical energy
Energy is transferred when chemical reactions take place, the energy stored in fuels
Electrical energy
Energy transferred by an electrical current
Elastic potential energy
Energy stored in a springy object
Elastic potential energy formula
½ x spring constant x extension²
½ x k x e²
K = spring constant (newtons per metre, N/m)
Kinetic energy
The energy of a moving object
Kinetic energy formula
½ x mass x velocity²
½ x m x v²
Gravitational potential energy
The energy of an object due to its position
Gravitational potential energy formula
Mass x gravitational field strength x height
m x g x h
Conservation of energy
Energy cannot be created or destroyed, can only be changed from one form to another
Work done
Energy is transferred from one store to another
Work done formula
Force x distance
F x D
Power
Rate of doing work
Power formula
Energy / time
E / T
Wasted energy
Dissipated into surroundings in the form of heat
How can energy be transferred?
Mechanically - work is done by force
Electrically - work is done by moving charges
Heating - conduction and convection
Specific heat capacity practical
Place the immersion heater into the central hole at the top of the block
Place the thermometer into the smaller hole and put a couple of drops of water into the hole to make sure the thermometer is surrounded by hot material
Fully insulate the block by wrapping it loosely with materials
Record the temperature of the block
Connect the heater to the power supply and turn it off after ten minutes
Specific heat capacity formula
Change in thermal energy / mass x temperature change
ΔJ / m x ΔT
M = mass (kilogram, kg)
ΔJ = change in thermal energy (joules, J)
ΔT = temperature change (celsius, °C)
Efficiency
A measure of how well an object outputs useful energy, compared to how much energy is taken in
Efficiency formula
Useful power output / total power input
Fossil fuels (non-renewable)
Oil, coal, natural gas
High power output
Releases CO2
Nuclear fuels (non-renewable)
Very high power output
Radioactive waste is hard to store
Biofuel (renewable)
Medium power output
Carbon neutral - no effect on the environment
Takes up space for farming
Wind (renewable)
Very low power output
Takes up large areas that can be used for farming and is an eye saw
Hydroelectricity (renewable)
Medium power output
Local residents are affected by noise pollution
Geothermal (renewable)
Medium power output
Very low impact on the environment
Sun (renewable)
Fluctuating power output
Depends on the weather
Burning fossil fuel process
The fossil fuel is burnt to boil H2O and turn it into steam
The steam turns the turbines
The turbines spin powering the generator
Step-up transformers increase the voltage and connect this to the National Grid
Step-down transformers decrease the voltage before feeding it to homes
Nuclear power stations
Nuclear uranium fuel rods heat water
The water turns into steam in the boiler
The steam turns the turbine
The turbine powers the generator which creates electricity
The electricity is sent through transformers which are sent to homes
Nuclear fission process
Neutron hits the uranium nucleus
Uranium nucleus splits into smaller nuclei and some more neutrons
These neutrons hits more uranium nuclei and the process continues
Wind turbines
Wind turns a turbine
Turbine powers a generator
Generator creates energy
Solar cells
The solar panel absorbs the sunlight
The panel converts sunlight to DC current
Hydroelectric
Water is held behind a dam in a reservoir high up a mountain
Rainfall fills the reservoir
When energy is needed, the water is allowed to run down through pipes to another reservoir lower down the mountain
As the water runs through the pipes it spins turbines that are linked to generators
The water can be pumped back up during the night when electricity is cheaper
Tidal barrages
The barrage gates close, trapping water as the tide rises
As the tide falls, water is released through turbines in the barrage, generating electricity from the moving water
During low tide, water flows back into the estuary as the tide rises again, potentially generating additional power
Geothermal
Heat and steam generated from volcanoes are extracted
The steam or hot water is used to drive turbines connected to generators, producing electricity
The cooled water is often re-injected into the ground to sustain the reservoir
Biofuel
Organic matter like crops or waste is harvested
Biomass is processed into biofuels, such as ethanol or biodiesel
The biofuels are used as an alternative to fossil fuels in vehicles, electricity generation, or heating
Carbon capture
When carbon is captured and stored underground
