The concepts of thrust and pressure are often confused. Answer the following questions to clarify the ideas.
(i) Define thrust and pressure, stating their SI units.
(ii) Starting from the relation between these quantities and the area of contact, prove algebraically that, for a constant thrust, the pressure on a surface is inversely proportional to the area of contact.
(iii) Using the conclusion reached in part (ii), explain qualitatively why:
(a) a camel with broad feet can walk easily on desert sand whereas a horse cannot,
(b) the tip of a drawing pin is made sharp while its head is kept broad.