Energy Flashcards
What is energy?
- We need energy to walk, to lift objects, to push, to pull and to think
- We get our energy from food and it is transferred into other forms of energy such as kinetic energy and heat energy
- Energy is the ability to work e.g. to make something happens or to have the potential to do so
Energy types
Chemical, heat, sound, light, electrical, gravitational potential, kinetic, elastic potential, nuclear
Chemical energy
Energy that is stored (potential) in food or batteries which can be transferred into other forms of energy. It is the energy stored in chemical bonds
Internal/ Heat energy
The wasted energy in many energy transfers is usually this. Most energy is wasted by turning into this. Thermal energy refers to the transfer of heat energy (from a Bunsen burner flame to increase the internal energy of. beaker of water
Sound energy
A series of longitudinal waves detected by our ears. Can also be another example of wasted energy e.g the hum from a fridge
Light energy
A series of electromagnetic detected by the eye. e.g. the light bulb emits this energy
Electrical energy
Arguable our most useful form of energy. Devices we use transfer this form of energy to other useful forms e.g the light bulb
Gravitational potential
A form of stored energy that varies depending on where you are in a gravitational field. The higher up you are, the more GPE you have
Kinetic energy
The energy stored in an object. Electrical motors transfer electrical energy to kinetic energy in devices such as hairdryers, food, mixers, etc
Elastic potential energy
Energy stored in an object such as a spring that is stretched, squashed or bent. It’s sometimes referred to as strain energy or simple, elastic energy
Nuclear energy
Nuclear energy is energy in the nucleus of an atom. This energy can be released when unstable uranium atoms in a nuclear reactor split apart in a process known as nuclear fission
Energy transfer and efficiency
- When we run, chemical energy from our food is converted into kinetic energy. Some of it is wasted by being transferred into thermal energy, making us hot and increasing our internal (heat) energy
- When a portable fan is used, chemical energy from a battery is converted into electrical energy, transferred along wires to a motor which then converts it into kinetic energy. Some energy is wasted as sound. Energy is also wasted because the internal energy of wires increases as they get warm
- Energy will never disappear. It can only be wasted or converted into other forms of energy. This is known as the law of conservation of energy “energy connoted be created or destroyed in any process. It can only be transferred from on type of energy to another”
Energy transfer
When we are considering energy transfers, we must remember that a proportion of the energy input is wasted. We can never have 100% efficiency. The useful output energy will always be less that the input
Formula for efficiency
Efficiency= useful energy output/ total energy input
Power
- Power rating of a motor driven pulley system tells us how quickly it transfer electrical energy into GPE
- Power is the rate of transfer of energy or work
- Power (P) is measured in watts (W). 1 W is equal to a transfer of 1J of energy per seco
Formula for power
Power= work done/ time taken
Energy resources
- A renewable source of energy can be used over and over again. There is an unlimited supply e.g. wood as trees can be grown, water is unlimited, wind
- Non-renewable energy sources will eventually run out and cannot be replaced e.g. coal because it takes a long time to form and we are using it a very fast rate
Wind
- Wind is caused by huge convection currents in the Earth’s atmosphere, driven by heat energy from the sun. This moving air has huge amounts of kinetic energy which can be transferred into electrical energy using turbines
- KE -> Electrical energy
- Wind is renewable, no CO2, but it is very noisy and wind turbines are ugly
Waves
- Waves are caused by the action of the wind upon the sea. Wave machines use the up and down movement of waves and air in a chamber to work electricity generators
- KE -> Electrical energy
- Renewable, no greenhouse gases but hard to build and expensive
Tides
- Tidal barrages are built across the mouths of rivers entering the sea. As water moves in and out of the river mouth when the tide turns, kinetic energy is used tow rod electricity generators
- Ke -> electrical
- Renewable, no Co2, but expensive, harms wildlife and requires the right geography
Hydroelectric
- These power schemes store water high up behind dams. The water has gravitational potential energy. As water rushed down through pipes, this GPE is transferred to kinetic energy, which turns electricity generators
- Ke -> electrical
- Renewable, no CO2 but ugly, disrupts wildlife, expensive
Geothermal
- In some places, rocks underground are hot because of radioactive decay. Deep wells can be drilled and cold water pumped down to be heated by rocks. It returns to the surface as hot water and steam, where its energy can be used to drive turbines and electricity generators
- thermal energy -> KE -> electrical
- Renewable, but deep drilling is difficult and expensive
Solar heating
- Solar panels do not generate electricity. Instead the sun is used to heat up water directly. A pump pushes cold water from a storage tank through pipes in the solar panel to be heated
- thermal energy -> electrical
- Renewable but sun’s energy varies
Solar cells
- Devices that convert light energy directly into electrical. Large arrays of solar cells are used to power road sings, and even larger arrays are used to power satellites in orbit around the Earth
- Light energy -> electrical
- Renewable, but sunshines varies, expensive and not super efficient
Fossil fuels
Coal, oil, natural gas are called fossil fuels. Chemical energy from the remains of plants and Dead Sea creatures that lived millions of years ago is stored within these. This energy is transferred to thermal energy and light energy when the fuels burn
- Chemical energy -> heat energy -> Kinetic energy -> electrical
- Efficient, reliable but non renewable and causes pollution
Nuclear power
- Heat from the chain reaction called by the fission of unstable uranium nuclei is used to boil water which produces steam, that turns turbines
- Nuclear -> thermal -> Kinetic -> electrical
- No greenhouse gases, cheap to run but expensive to build, nuclear waste
Biomass
- Fuels come from living things like wood. Chemical energy stored in these when burned is released as heat energy which heats up water into steam. Steam is then used to turn turbines which generate electrical
- Chemical -> Heat -> Kinetic -> electrical
- Renewable, carbon neutral but huge land area needed
