Force and Pressure — Question 13

First case :

Thrust = Weight = 2 kgf
Area = 20 cm x 10 cm = 200 cm²
Pressure = ?

$\text{Pressure}= \dfrac{\text{Thrust}}{\text{Area}} \\[1em] = \dfrac{\text{2}}{\text{200}} \\[1em] = 0.01 \text{ kgf cm}^{-2}$

So Pressure exerted by brick in first figure is 0.01 kgf cm^-2.

Second case :

Thrust = Weight = 2 kgf
Area = 5 cm x 10 cm = 50 cm²
Pressure = ?

$\text{Pressure}= \dfrac{\text{Thrust}}{\text{Area}} \\[1em] = \dfrac{\text{2}}{\text{50}} \\[1em] = 0.04 \text{ kgf cm}^{-2}$

So Pressure exerted by brick in second figure is 0.04 kgf cm^-2.

Third case :

Thrust = Weight = 2 kgf
Area = 20 cm x 5 cm = 100 cm²
Pressure = ?

$\text{Pressure}= \dfrac{\text{Thrust}}{\text{Area}} \\[1em] = \dfrac{\text{2}}{\text{100}} \\[1em] = 0.02 \text{ kgf cm}^{-2}$

So, Pressure exerted by brick in third figure is 0.02 kgf cm^-2.