EnergySarah Jones

http://fabianoefner.com

http://fabianoefner.com

Work• When a force (Newton, N) moves an object

work is done.• Work is a measure of the amount of energy

(Joules, J) used in moving the object.

work done = force applied x distance movedW = F x d

http://www.bbc.co.uk/bitesize/

Force Diagrams

• Thrust – a forward push• Upthrust – the upwards force on a body in a

liquid or a gas

Power• Power (Watts, W) is the rate that work is done

– how fast energy is used.

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Kinetic Energy• The energy of motion.• All moving things have kinetic energy.

painincorporated.com

Calculating kinetic energyEk = ½mv2

m = mass of object (kg)v = the objects speed (m/s)

www.cyberphysics.co.uk

Potential Energy• An object can store energy – this is dependent

on position.• Includes - gravitational, chemical and elastic

energy.

www.physicsclassroom.com

Electrical Energy Kinetic Energy

Kinetic Energy Electrical Energy

Electrical Energy Sound Energy

Electrical Energy Heat Energy

Light Energy Electrical Energy

Elastic Energy Kinetic Energy

Chemical Energy Heat Energy

Gravitational Energy Electrical Energy

Gravitational Energy Kinetic Energy

Gravitational Potential Energy

Ep = mgh

m = mass (kg)g = acceleration due to gravity (9.8 m/s2)h = height (m)

http://www.bbc.co.uk/schools/gcsebitesize

Law of Conservation of Energy

• States that energy cannot be created or destroyed, just transformed from one form to another.

– Therefore, energy never ‘disappears’.

– Energy that is transferred to unwanted forms is wasted energy.

Et = Ep + Ek

www.physicsclassroom.com

Energy Conversion Efficiency• Some energy can be ‘lost’ as heat and sound.• Energy is lost in the form of heat and sound

each time the rollercoaster moves. If this did not occur the rollercoaster would keep on moving forever.

Television

Electrical Light, Sound and Heat

StereoElectrical Sound and Heat

Car Engine

Chemical Kinetic, Sound and Heat

Energy Transfers - Boardworks

Light BulbsElectrical Energy Light and Heat