Question

A girl weighing 50 kg is standing on a pencil heels. Each having an area of cross-section 1cm². An elephant weighing 200 kg and foot area of cross-section of 250 cm² standing on the floor. Which of the two exerts more pressure on the floor? (Given acceleration due to gravity = 10 m/s²)

Answer 1

Weight of the girl = 50 kg (Given)
Area of the cross-section = 1 cm² (Given)

$\mathrm{P}=\frac{\mathrm{Force}}{\mathrm{Area}}$

Force = Weight of the body = 50 kg

$\mathrm{Pressure},\mathrm{P}=\frac{50\mathrm{kg}}{1{\mathrm{cm}}^{-2}}$

1 cm = $\frac{1}{100}$

$\therefore \mathrm{P}=\frac{50}{{\displaystyle \frac{1}{10000}}}$

P = 500000 Nm^–2

Weight of the elephant, W = 200 kg
Area of the cross-section of foot A = 250 cm²
A = 0.0250 m²

Pressure exerted by the elephant on land:

$$\begin{gathered} \mathrm{P}=\frac{\mathrm{Force}}{\mathrm{Area}}=\frac{200}{0.0250}=\frac{2000000}{250} \\ \mathrm{P}=8000{\mathrm{Nm}}^{-2} \end{gathered}$$