Non-contact forces

Non-contact forces are forces that act between two objects that are not physically touching each other.

Example: Magnetic force

A magnetic force is experienced by any magnetic material in a magnetic field.

Opposite magnetic poles (N - S or S - N) attract each other – but do not need to be in contact.

Two magnets are next to each other with North and South poles facing one another. Two equal arrows between the poles of the magnets point inwards towards each other.

Like magnetic poles (N - N or S - S) repel each other – but do not need to be in contact.

Two magnets are side by side with North poles facing each other. Two arrows between the poles of the magnets point outwards away from each other.

Key points

  • Force is measured in newtons N.
  • Force is a vector quantity - direction is important as well as size.
  • A force acting in one direction is given a positive value.
  • A force acting in the opposite direction is given a negative value.

When forces act between two objects, both objects experience an equal size force, but in opposite directions.

This is Newton's Third Law of Motion.