physics revision

autumn assesment revision physics

Chemical energy store

energy stored in the chemical bonds between atoms etc apples, fuel

Kinetic energy store

energy stored in moving objects etc ball, car

Gravitational potential

when an object is stored out in a height in a gravitational field etc earth

Elastic potential energy

the energy stored in stretched objects etc elastic bands

Thermal energy store

Energy stored in relation to heat etc heater

electrostatic store

energy stored in an electric field between charged particles etc hair upper machine

magnetic store

energy stored in a magnetic field between 2 poles

Energy can’t be…

created or destroyed only transfered

Energy transfers in 4 ways-

mechanically,electrically,heating,radiation

mechanically

a force moving through a distance

electrically

charges moving through a potential difference

heating

due to a temperature difference

radiation

energy transferred by a wave

work done

force moves an object it does work and energy is transferred to the object

Work done equation-

work done= force (N) times distance (m)

Ep ( gravitational potential energy)

when an object falls or gains height or changes its position relative to Earths gravitational pull

Gpe/ Ep equation

Gpe = mass times gravitational field strength times change in height

Kinetic energy/ Ek

½ mass times volocity squared

Volocity equation=

another way to find elastic potential energy..

½ spring constant times extention squared

whats the most common waste energy

thermal energy store

efficiency equation

useful energy transferred divided by energy supplied times 100

useful energy equation

total input energy - waste energy

efficiency

efficiency is a measure of how much useful energy is produced by a process compared to the amount to the amount of energy put in

how to reduce waste energy

thermal insulation/ double glazing/ carpet/lubrication

power

how fast the ‘work done’ is completed

power equation

power = energy transferred divided by time taken ( P= W divided by T)

units of power

power- watts/ energy- joules/ time- seconds