1.7 Energy, work and power - IGCSE Physics

Energy Stores

-Energy may be stored as kinetic, gravitational potential, chemical, elastic (strain), nuclear, electrostatic and internal (thermal)

Chemical Energy

-Food and fuels, like oil, gas, coal and wood, are concentrated stores of chemical energy

-The energy of food is released by chemical reactions in our bodies, and during the transfer to the other stores we are able to do useful jobs

-Fuels cause energy transfers when they are burnt in an engine or a boiler

-Batteries are compact sources of chemical energy which in use is transferred by an electric current

GPE

-This is the energy an object has because of its position

-A body above the Earth's surface, like water in a mountain reservoir, has gpe

Elastic strain energy

-This is energy an object has because of its condition

-Work has to be done to compress or stretch a spring or elastic material and energy is transferred to ESE

KE

-Any moving object has KE and the faster it moves, the more KE it has

Electrostatic Energy

-Energy can be stored by charged objects as electrostatic energy

-This energy can be transferred by an electric current

Nuclear Energy

-The energy stored in the nucleus of an atoms is known as nuclear energy

-It can be transferred to other energy stores in nuclear reactions such as fission and fusion

Internal energy

-This is also called thermal energy and is the final fate of other energy stores

-It is transferred by conduction, convection or radiation

Energy Transfers - Refer Coursebook

Measuring energy transfers

-In an energy transfer, work is done

-The work done is a measure of the amount of energy transferred

-Energy, as well as work, is measured in joules (J)

-Work = force x distance moved in the direction of force

Principle of conservation of energy

"Energy cannot be created or destroyed; it is always conserved

Refer Coursebook for rest of the contents