Energy Flashcards
Explain kinetic energy.
Moving things have kinetic energy. The heavier a thing is and the faster it moves the more kinetic energy it has. All moving things have kinetic energy, even very large things, like planets, and very small ones, like atoms.
Explain sound energy.
A vibrating drum and a plucked guitar string transfer energy to the air as sound. Kinetic energy from the moving air molecules transfers the sound energy to your eardrum.
Explain thermal energy.
Thermal energy is what we call energy that comes from heat. A cup of hot tea has thermal energy in the form of kinetic energy from its particles. Some of this energy is transferred to the particles in cold milk, which you pour in to make the tea cooler.
Explain chemical energy.
Some chemical reactions release energy. For example, when an explosive goes off, chemical energy stored in it is transferred to the surroundings as thermal energy, sound energy and kinetic energy.
Explain electrical energy.
A battery transfers stored chemical energy as electrical energy in moving charges in wires. For example, electrical energy is transferred to the surroundings by the lamp as light energy and thermal energy.
Explain gravitational potential energy.
A rock on a mountain has stored energy because of its position above the ground and the pull of gravity. This energy is called gravitational potential energy. This is the energy it would release if it fell. As the rock falls to the ground, the gravitational potential energy is transferred as kinetic energy.
What do energy transfer diagrams show?
The locations of energy stores and energy transfers.
What do sankey diagrams do?
Summarise all of the energy transfers taking place.
What is heat?
The amount of thermal energy it contains.
What is temperature?
How hot or cold something is.
What is heat measured in?
Joules.
What is temperature measured in?
°C
How can thermal energy be transferred?
Conduction, convection and radiation.
Explain conduction.
When a substance is heated, its particles gain energy and vibrate more vigorously. The particles bump into nearby particles and make them vibrate more. This passes the thermal energy through the substance by conduction, from the hot end to the cold end.
Explain convection.
The particles in liquids and gases can move from place to place. Convection happens when particles with a lot of thermal energy in a liquid or gas move, and take the place of particles with less thermal energy. Thermal energy is transferred from hot places to cold places by convection.
Explain radiation.
All objects transfer thermal energy by infrared radiation. The hotter an object is, the more infrared radiation it gives off.
No particles are involved in radiation, unlike conduction and convection. This means that thermal energy transfer by radiation can even work in space, but conduction and convection cannot.
How is radiation different to conduction and convection?
Conduction and convection need moving particles to transfer energy whereas radiation does not.
What is the difference between renewable and non-renewable energy?
Non-renewable energy resources cannot be replaced once they are all used up.
Renewable energy resources can be replaced, and will not run out.
Name three fossil fuels.
Coal, oil and natural gas.
Name some forms of renewable energy.
Biomass, wind power, water power, geothermal, solar cells, solar panels.
Explain biomass.
Biomass fuels come from living things. Wood is a biomass fuel. As long as we continue to plant new trees to replace those cut down, we will always have wood to burn. Just as with the fossil fuels, the energy stored in biomass fuels came originally from the Sun.
Explain wind power.
Wind is caused by huge convection currents in the Earth’s atmosphere, driven by heat energy from the Sun. The moving air has huge amounts of kinetic energy, and this can be transferred into electrical energy using wind turbines. Wind turbines cannot work if there is no wind, or if the wind speed is so high it would damage them.
Explain water power.
Moving water has kinetic energy. This can be transferred into useful energy in different ways. For example: Wave machines use the up and down movement of waves to turn electricity generators. Tidal barrages are built across the mouths of rivers. As water moves in or out of the river mouth when the tide turns, the kinetic energy in the water is used to turn electricity generators. Hydroelectric power (HEP) schemes store water high up in dams. The water has gravitational potential energy which is released when it falls. As the water rushes down through pipes, this stored energy is transferred to kinetic energy, which turns electricity generators.
Explain geothermal.
In some places the rocks underground are hot. Deep wells can be drilled and cold water pumped down. The water runs through fractures in the rocks and is heated up. It returns to the surface as hot water and steam, where its energy can be used to drive turbines and electricity generators.