Energy Flashcards
What is energy measured in?
Joules (J)
What are the five energy stores?
Thermal Elastic potential Chemical potential Gravitational potential Kinetic
Describe a thermal energy store.
All objects have thermal energy. It is the energy a substance has due to its kinetic energy (movement) of its particles. The more thermal energy a material has, the hotter it is.
Describe an elastic potential energy store.
When materials are stretched and have the potential to return to their original shape they store elastic potential energy. The same goes for squashed materials.
Describe a chemical potential energy store.
A type of stored energy that is released by chemical reactions. Fuels, foods and batteries all contain chemical energy.
Describe a gravitational potential energy store.
Any object in a gravitational potential field has gravitational potential energy due to its position in that field.
Describe a kinetic energy store.
Kinetic energy is the energy an objet has because it is moving.
Since energy cannot be created or destroyed, what can it do?
It can be transferred.
What are energy stores classified as in energy transfers?
Useful or not useful.
what is the formula for work done?
Work done (J) = force applied (N) x distance moved along line of action of force (M) W=FxS
What is the formula for weight?
Weight (N) = mass x GPE
What is the formula for mass?
Kinetic Energy
———————
1/2 x velocity^2
What is the formula for kinetic energy?
KE (J) = 1/2 x mass x velocity^2
What is the formula for velocity?
___________
|kinetic energy
|——————
| 1/2 x mass
What is the formula for elastic potential energy?
E (EPE) = 1/2 x k (spring constant) x e^2 (extension^2)
What is the formula for power?
Energy transferred/time
What is the formula for efficiency?
(Useful energy output/total power input)x100
What happens to an elastic object when the forces deforming it are removed?
Regains original shape.
Define specific heat capacity.
How many joules of heat energy are needed to raise the temperature of each kilogram by 1’C.
What is the formula for change in energy?
🔺E = m (mass kg) x c (specific heat capacity J/kg’C) x 🔺Θ (change in temperature ‘C)
What is the Law of Conservation of Energy?
Energy = energy cannot be created or destroyed.
Define dissipated energy.
Wasted energy spreading into the surroundings.
Define conduction.
Energy transferred through collisions between neighbouring vibrating particles. Only takes place in solids.
Define convection.
Energy transferred through rising regions of a fluid. Takes place in liquids and gases.
Define radiation.
Energy transferred by electromagnetic radiation. Takes places through free spaces.
Define evaporation.
Energy transferred away from surface of a liquid by escaping high energy particles.
Define condensation.
Energy transferred to a solid by gas forming a liquid on the surface.
What is the formula for specific heat capacity?
🔺E / m x 🔺degrees
