What is energy measured in?
Energy is measured in joules (J) or kilojoules (kJ).
What are the eight energy stores?
The eight energy stores are Thermal, Kinetic, Elastic, Gravitational, Chemical, Magnetic, Nuclear, and Electrostatic.
What are the pathways of energy?
Energy pathways include mechanical, heat, electrical, light, and sound.
What is the conservation of energy?
Energy cannot be created or destroyed; it is transferred between stores.
What is fuel?
A material that contains a store of chemical energy.
What is useful energy?
Energy that has been transferred into the required form.
Example: A combustion engine transfers the chemical energy store in fuel into the kinetic store of the moving parts of the engine.
What is wasted energy?
Energy transferred into a form that is not required.
Example: A TV transfers some electricity into thermal energy.
What is efficiency?
The proportion of energy usefully transferred, calculated by useful energy output divided by total input energy.
What does a Sankey diagram show?
It shows the proportion of energy transferred into useful and wasted energy.
What is temperature?
A measure of how hot or cold something is.
What is heat?
An energy pathway.
What is infrared?
An electromagnetic wave (light ray) that transfers thermal energy.
What does it mean to absorb?
To take in.
What does it mean to emit?
To give out.
What is conduction?
Heat transfer through solids, where vibrating particles pass on energy to the next particle.
What is convection?
Heat transfer through fluids (liquids and gases). As particles gain thermal energy, they become less dense and float; as they cool down, they sink.
What is thermal radiation?
The emission of electromagnetic waves (infrared light rays) from all hot objects.
What is thermal energy?
The kinetic energy of random movements of atoms and molecules in matter.
What is work done?
Measured in joules or newton metres (1J = 1Nm), it is a measure of the energy transferred to or from an object which allows it to be moved.
How is work done calculated?
Work done (J or Nm) = force (N) X distance (m).
