Energy (physics) Flashcards
Name the 5 energy stores…
Thermal Kinetic Chemical Elastic potential Gravitational potential
What is the conservation of energy law…
ENERGY CANT BE CREATED OR DESTROYED
Energy I measured in
Joules
Explain what happens when energy ‘dissipates’…
Some energy dissipates into the surroundings (it spread out into the surroundings). Normally this is by friction heating up the surroundings or sound/light waves.
Thermal energy…
- All objects have it
- it is the energy a substance has due to its kinetic energy of its particles
Elastic potential…
- When objects stretch they have the potential to return to their original shape.
- Likewise when you squash a material
Kinetic energy….
Energy stored be a an object is moving
Gravitational potential energy…
Energy an object passes due to its position in a gravitational field
Work =
Work= force x distance
Weight =
Weight = mass x gravitational field strength (kg & N/kg)
Kinetic energy =
Kinetic energy (J) x mass x 1/2 x velocity^2
Power=
Power = Energy/time
How do you calculate efficiency?
Efficiency = (useful power output/total power input ) x100
Work is …
Moving about a force
Chemical potential energy
- Chemical energy is a type of stored energy that is released by a chemical reaction
- feul food and batteries contain chemical potential
What is specific heat capacity?
Specific heat capacity is the amount of energy required to raise the temperature of 1 kg of a substance by 1°
what does friction have to do with energy?
Friction causes energy to be transferred to thermal energy. The store is a thermal energy and less useful, the energy has been dissipated/wasted.
Specific heat capacity (this equation is given in the exam)
Energy transferred = mass(kg) x SHC (J/kg°C) x temperature change (°C )
Conduction is ….
Energy transferred three collisions between neighbouring vibrating particles, this only takes place in solids.
Convection is …
Energy transferred from rising regions of a fluid. Takes place in liquids and gases
Radiation is…
Energy transferred by electromagnetic radiation. Takes place in liquids and gases -for example energy reaching us from the Sun
Evaporation is…
Energy transferred away from the surface of a liquid by scraping high energy particles. And example of this is cooling of a hot drink.
Condensation is….
Energy transferred to a solid by a gas forming a liquid on the service – for example the missing of mirrors and windows.
What is meant by a renewable energy source?
An energy source which is replenished by natural processes as it’s being used
Name three examples of renewable energy sources:
- solar
- hydroelectric and tidal
- wind (wind turbines)
- geothermal
- biofuels
What is specific LATENT heat?
Is the amount of energy needed to change 1 kg of the substance from one state to another without changing its temperature
What is the equation for specific latent heat?
Energy (j) = mass (kg) x latent heat (j/kg)
