Force is anything that causes the velocity of an object to change.

• Force has direction in which it acts – it is a vector quantity.
• The symbol for force is F.
• The unit of force is the newton (N).
• Acceleration of a body is directly proportional to the force causing it, i.e. for a given body:

## Mass

The mass (m) of a body is a measure of how difficult it is to accelerate that body.

• The unit of mass is the kilogram (kg).
• Acceleration of a body is
• i.e for a given... (More)