What a chemical energy store?
The energy stored in chemical bonds between molecules
Examples:
-batteries
-food
-fuel
-muscles
What is a kinetic energy store?
The energy of a moving object
Example:
-runners
-buses
What is a gravitational potential energy store?
The energy of an object at height
Example:
- aeroplanes
-Mugs on a table.
- books on a shelf
What is a thermal/internal energy store?
The total energy of particle in the object
Example:
-hot coffee
- human body
What is an elastic potential energy store?
The energy stores when an object is stretched or squashed
Example:
-Elastic band
-Spring
What is magnetic energy store?
The energy stored when repelling poles have been pushed closer
Examples:
- fridge magnets
-compasses
What is an electrostatic energy store?
The energy stored when repelling charges have been moved closer together
Example
-van de graaff generator
What is a nuclear energy store?
The energy stored in the nucleus of an atom
Example
Nuclear reactor
How can you increase an energy store?
Heat
Electricity
Radiation/waves light and sound
Mechanical
What is the law of conservation of energy?
Energy can not be created or destroyed it can only be transferred from one store to another
Why does a ball when dropped not return to its original height?
The ball has a store of g.p.e but once it is dropped the gp.e energy store decreases as the kinetic energy store increases. Energy is transferred to the surrounding through mechenical transfer by increasing the ball and surfaces thermal energy store and by sound waves
Once the ball hits the surface it bounces upwards, increasing the g.p.e. energy store and decreasing the kinetic energy store. It does not bounce back up to the oniginal drop height. Eventually it stops bouncing
What is work?
Work is the amount of energy transferred (changed) when a force moves (in the direction of the force)
Why do brake pads on cars get really hot?
Friction between the break pads and the wheel discs opposes the motion of the wheel. The friction does work on the brake pads and dics
What is friction?
Friction is the opposing force to direction or movement when two surfaces are in contact
What is gravitational potential energy?
When an object is lifted in a gravitational field energy is transferred to a gravitational potential store.
What is kinetic energy?
The energy an object has because of its mass and velocity.
What is a spring constant?
Every spring has its own spring constant. It is a numerical value of the stiffness of the spring.
The stiffer the spring the greater the spring constant.
What is the equation for kinetic energy?
Kinetic energy =1/2 x mass x velocity
What is useful energy?
Energy transferred to where is wanted and in the form it is wanted in
What is wasted energy?
Energy that is not transferred usefully
What happens to wasted energy?
Wasted energy is eventually transferred to the surroundings which become warmer. This dissipated energy is too spread out to do useful work and so cannot be reused. This is why it is important to reduce the amount of energy that is wasted
What is efficiency?
Efficiency means performing in the best way with the least waste of time or effort.
Energy efficiency is about getting as much useful energy output as possible from a device
What is the equation for energy efficiency?
Energy efficiency = useful output energy/ total input energy
What is power?
Power means the rate at which energy is transferred. It is measured in watts
