Energy and Change:
Subject List
Energy and its uses

Energy

Things such as a heater warming a room, a flashlight illuminating the darkness, the music from a piano and a child running a race all happen because energy is changed (transformed) from one form to another.

The idea of energy is abstract and as such is difficult for children to understand but they enjoy identifying how energy is transformed.

The big point to remember here is:-

Energy cannot be created nor destroyed, it can only be:

  • Stored - like in a battery, in body fat or in food.
  • Transferred - like when electrical energy is moved through wires.
  • Transformed to another form of energy - like when a light glows when switched on or when a rocket rises into space on a plume of hot gases.

Transfer of energy

Energy can travel along or through certain materials or be transferred through space as electromagnetic radiation or light.

Examples of energy transfer are:

  • When water is being boiled heat energy is transferred from the hotplate to the water through the bottom of the saucepan.
  • Electrical energy being transferred along power lines.
  • Light travelling to Earth through space from the Sun.

Storage of Energy

All objects have a certain amount of stored energy within the substance due to the presence of chemical, electrical, thermal and potential energies. These energies combined are referred to as internal energy.

Fuels and food are two examples of substances with large amounts of internal energy that can be readily accessed by chemical reactions such as burning or digestion.

Batteries are capable of delivering their stored internal energy as electricity, rather than as thermal energy. Burning wood transforms some of the internal energy of the wood into thermal and light energy. Digestion delivers some of the stored internal energy of food as thermal energy and chemical energy to be used by the body. Note: Not all of the internal energy is transformed in these processes as some is always left in the products and waste left by these processes.




Transformation of Energy
Transformation of energy occurs whenever energy is used to make a change:

  • When a light bulb is turned on - electrical energy is transformed to light energy.
  • When food is used in our bodies - chemical energy is transformed to thermal energy and kinetic energy.
  • When a storm blows - thermal energy from the Sun is being transformed to kinetic energy in the movement of the air.
  • When wood burns - stored chemical energy is transformed to thermal and light energy.
  • When petrol is used in a car engine - stored chemical energy is transformed to thermal and kinetic energy of movement.

Links:
Electrical energy Sound energy Heating Kinetic and potential energy Light energy
Heat, heating and thermal energy Transformation of chemical energy
Transformation of solar energy Energy generation Magnetic force and moving charge
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