Question

A cuboid of mass 2 kg and dimensions 3 cm x 5 cm x 20 cm. If g = 10 m/s2 , find the maximum pressure and minimum pressure exerted by this solid on the surface.

Answer 1

Minimum pressure exerted (when area is maximum) = 2× 10/ 0.2×0.05
= 20/0.010 = 2000 N/m²
Maximum pressure(when area is least) = 2×10/ 0.03×0.05 = 20/ 0.0015 = 200000/15 = 13333.33 N/m²

Answer 2

The max pressure would be 13333.33 Pa and minimum would be 2000 Pa

1) Mass of cuboid = 2 kg

and g = 10 m/ s^2

The force exerted by the cuboid would be

F = mg = 2*10 = 20 N

2) The formula for pressure is

P = F/A

Hence, pressure is inversely proportional to the area i.e. minimum the area, higher would be the pressure and vice versa

3) The area of three sides of the cuboid would be

3*5 = 15 cm^2 = 0.0015 m^2

5*20 = 100 cm^2 = 0.01 m^2

3*20 = 60 cm^2 = 0.06 m^2

4) Hence, pressure would be minimum at side with dimensions 5 and 20

P = 20/0.01 = 2000 Pa

Pressure would be maximum at side with dimension 3 and 5

P = 20/ 0.0015 = 13333.333 Pa