Classify the following amongst contact and non-contact forces —

(a) frictional force, (b) normal reaction force, (c) force of tension in a string, (d) gravitational force, (e) electrostatic force, (f) magnetic force.

Define a contact force.

Give one example in each case where —

(a) the force is of contact, and

(b) force is at a distance.

State one factor on which the magnitude of a non-contact force depends. How does it depend on the factor stated by you?