Question

Find the pressure exerted by a boy of 90kg.
(a) when he is standing on one of his feet having an area of 90cm2

Answer 1

P = F/a

 FROM NEWTON'S SECOND LAW OF MOTION

⇒ F=ma (here acceleration is under gravity, therefore a = g(acceleration due to gravity)

∴ F= W(weight) = mg

Mass = 90 kg; g = 10m/s²

⇒ F=W= 90 * 10 = 900N

P = Force/area

(a) Area= 90cm² = 0.009 m²

∴ P = 900/0.009 = 90000/9 = 10000 Pa or N/m²