Category: Energy, Work and Power

Gravitational potential energy is the energy a body has due to its height above ground.

Kinetic energy is the energy a body in motion possesses.

Energy is the ability to do work.

Power is the rate of work done, or the rate of energy conversion.

Work done is the product of a force, and the distance moved by the body, in the direction of the force.

Energy can be transferred from one store to another:

i) Mechanically (by a force acting over a distance)
Eg: a car moving up an inclined plane
      (chemical potential energy –> gravitational potential energy)

ii) Electrically (by an electric current)
Eg: lighting up a bulb in an electric circuit
(chemical potential energy of battery –> light and heat energy of light bulb)

iii) By heating (due to a temperature difference)
Eg: a gas stove heating up a pot of water
(chemical potential energy of gas –> internal energy of water)

iv) By propagation of waves (both electromagnetic and mechanical)
Eg: a dipper producing surface water waves
(mechanical energy of dipper –> kinetic energy of water waves)

An energy store is a substance or a physical system that can store energy in various forms.
Some examples of energy stores are:
– batteries (chemical potential energy)
– a stretched spring (elastic potential energy)
– fuels (chemical potential energy)
– a dammed water body (gravitational potential energy)
– tidal waves (kinetic energy)
– radioactive isotopes (nuclear energy)

The Principle of the Conservation of Energy states that energy cannot be destroyed or created.

It can only be converted from one form to another, or transferred from one body to another.

The total energy in the system remains constant.