Force may be classified into the following two classes —
- Contact forces : The contact forces represent the result of physical contact between two objects, one by which force is exerted and the other on which forces exerted.
Example — (1) Pulling (stretching) of a coiled spring, pulling of a cart/pram and kicking of a football are some examples of contact forces.
(2) The force exerted on us by the wind is also a contact force.
- Action-at-a-distance forces : The action-at-a-distance forces are the forces which do not involve physical contact between the two objects but act through the space between the two.
Example — The gravitational force, electrical force, and magnetic action-at-a-distance forces.