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Energy can be neither created nor destroyed but changed from one form into another. When energy is changed from one form into another a different form of energy is formed. For example when petrol burns in a car engine the chemical potential energy of stored in the petrol produces the kinetic energy of motion. This is represented by an energy equation:

Examples of Energy Equations:

Chemical potential energy from wax.
Chemical potential energy —–> light + heat energy

Chemical potential energy from petrol.
Chemical potential energy ——-> Kinetic energy of motion + sound and heat energy

Energy can exist in different forms.

• Energy can be changed from one form to another.

• Energy is not a tangible substance.

• Energy is only detected when some change occurs.

Energy is defined as the capacity to do work and is measured in Joules (J).

Examples of energy forms

• Food is chemical potential energy.

• Extending or compressing a spring is elastic potential energy.

• Gaining or losing height is gravitational potential energy.

• Noise is produced by sound energy.

• The stars in the night sky produce solar energy.

• A lead/acid car battery stores chemical potential energy.

• An atomic power plant produces nuclear energy.