4b - Energy Transfers

Types of transfers

electrically, radiation, mechanically, heating

Types of energy stores

Thermal, kinetic, gravitational potential, chemical, elastic, nuclear, magnetic, electrostatic

Kinetic

Energy store for moving objects.

Chemical

Energy stored by fuels, food or batteries

Gravitational Potential

The higher above the ground an object is, the more energy in its GP store.

Elastic

Energy stored by object that have been stretched or deformed.

Thermal

Transfers from hotter objects to colder objects.

Electrostatic

The energy store of separate charged particles

Magnetic

The energy store of (for example) two separated magnetic poles.

Nuclear

Energy store of the nuclei of atoms

Law of conservation of energy

Energy cannot be created or destroyed, only transferred.

Sankey diagrams

A diagram where the total energy input is equal to the useful energy output and the wasted energy output.

Efficiency calculation

efficiency = useful output/total input x 100

Conduction

When particles transfer energy to other particles by colliding with them.

States of conduction

Solids, liquids, gases but fastest in solids

Convection

A transfer of thermal energy that only occurs in fluids. It occurs because of a difference in density.

Convection vs conduction

Conduction is when energy is transferred between particles, whereas in convection, energy is transferred via the movement of particles from one place to another.

Convection current

The fluid is heated via convection, so it becomes less dense and rises. The hot particles move around, heating the rest of the fluid. The particles are pushed aside by more particles moving to be heated, so the particles cool down and sink. These particles push each other around, forming a convection current.

Good absorbers/emitters of infrared radiation

Black / Dull

Bad absorbers/emitters of infrared radiation

White / Shiny

Good reflectors of infrared radiation

Shiny