Energy Flashcards
What does the law of conservation of energy state?
Energy cannot be created or destroyed, only transferred.
Total energy before = total energy after.
What are ways of transferring energy?
Light, sound, and electricity.
What measurements do thermometers measure temperature in?
In degrees Celsius (°C).
What does temperature measure?
The average energy.
What does thermal energy measure?
The total energy.
Which has more thermal energy: a warm bath or a heated kettle?
A warm bath has more thermal energy than a heated kettle, even though the kettle has a higher temperature.
What happens to particles as we heat solids, liquids, and gases?
Particles gain more kinetic energy and vibrate more or faster.
What does the energy needed to heat an object depend on?
The mass, material, and temperature rise.
What is equilibrium in terms of thermal energy?
When objects have the same thermal energy.
What are renewable resources?
Resources that produce greenhouse gases when built, not when used, and will not run out.
Give examples of renewable resources.
Wind, tidal, wave, hydroelectric, geothermal, biomass, and solar powers.
How can thermal energy be transferred?
By conduction, convection, or radiation.
What is conduction?
Particles collide into others when they vibrate and occurs in solids.
What is convection?
Occurs in liquids or gases where the part in contact with the heat source gets hotter, causing particles to move faster and become further apart.
What is a convection current?
The cycle where hot parts rise and cooler, denser parts fall, continuing the heating process.
What are non-renewable resources?
Resources like coal, oil, and gas that cannot be reused and will eventually run out.
What is the energy content in food and fuels measured in?
Joules (J).
What is power?
The rate of energy transfer - how much energy is transferred each second.
How are energy bills measured?
In kilowatt per hour (kWh).
How do you convert kWh to joules?
Convert the time to seconds and multiply by the energy in joules per second.
For example, 2000J/s x 7200s = 14400000 J.
How can you reduce energy bills?
Use fewer appliances or more efficient ones, and insulate houses to lose less thermal energy.
What is the formula for work done?
Work done (J) = force (N) x distance (m).
What is infrared radiation?
A type of radiation that transfers energy without particles - it is a wave.
What factors affect the amount of radiation emitted by objects?
Their temperature and surface characteristics (colour and rough/smooth).
What is the energy content of an apple?
200 kJ per 100g.
What is the energy content of chips?
1000 kJ per 100g.
What is the energy used for sitting?
6 kJ per minute.
What is the energy used for running?
60 kJ per minute.
