Energy

10 Types:• Gravitational Potential• Electrical• Sound• Thermal/Heat• Radiant/Light• Elastic (strain)• Chemical• Nuclear• Kinetic• Magnetic

• Law of conservation of Energy:“Energy cannot be created or destroyed.

It can only be changed from one form to another.”

There are 10 forms energy can take:You must know these.

Gravitational Potential Energy

• This is energy of height. If you do work on an object against gravity it gains G.P.E..

• Formula: G.P.E.=Weight*Height

• E.g. You lift a 300N child by 40m.• How much work is done on him?• How much G.P.E. does he gain?

Electrical Energy

• This is simply energy delivered by electrical wires, by moving charge.

Light Energy

• This is energy transferred by light. A bulb gives out light energy.

Sound Energy

• Energy of sound- produced by vibrations.

Thermal (Heat) Energy

• Energy of hot objects

Radiant Energy (includes light energy)• Energy given out as

electromagnetic waves. E.g. the Sun emits ultraviolet waves which give the Earth energy.

Elastic (potential) Energy (strain)

• Energy stored in a stretched or compressed object.

Chemical Energy

• Energy that can be released in a chemical reaction.

• This includes energy from food released in respiration.

Nuclear Energy

• Energy stored in an atomic nucleus. It can be released in power stations.

Kinetic Energy

• This is energy of movement. Faster objects have more K.E.

• Formula: K.E.=½mv²

Magnetic (potential) energy

• The energy stored due to magnets

Energy changesWhat energy changes occur when the

following things happen?• (a) a battery lights a light bulb• (b) a boy lifts up a rock• (c) an arrow is fired from a bow• (d) a firework rocket moves upwards• (e) a car is braked to a stop on a level

road• (f) a firework explodes• (g) a CD player plays a CD• (h) a plant grows in the garden

Write the energy changes

a) A monkey climbs a treeb) A person acceleratesc) A piece of paper burnsd) A catapult fires a rocke) A plant photosynthesisesf) Water coolsg) 2 magnets push each other away