Question

(a) How can you differentiate between a contact force and a force at a distance? [2 marks]

(b) How do you increase the pressure by keeping (i) area unchanged and (ii) force unchanged? [2 marks]

Answer 1

(a) Contact forces are the forces that can be applied to a body by coming in direct contact with the body.
Examples of such forces are muscular and frictional forces.

Forces at a distance or non-contact forces are the forces that can be applied to a body without any direct contact.
Examples of such forces are magnetic, electrostatic, and gravitational forces. (2 marks)

(b) Since, Pressure (P) = $\frac{Force}{Area}$ , therefore,
(i) to increase pressure by keeping area unchanged we must increase the force perpendicular to the area and,
(ii) to increase pressure by keeping force unchanged we must decrease the area on which force is acting. (2 marks)