Question

The atmospheric pressure above a swimming pool changes from 753 to 761 mm of mercury. The bottom of the pool is a 20.8 m x 37.9 m rectangle. By how much does the force on the bottom of the pool increase?

Answer 1

Change in pressure = P = ( 761 - 753 ) mm mercury = 8 mm mercury = 0.008 m mercury.

Density of mercury = d = 13.6 x 10³ kg / m³.

Acceleration due to gravity = g = 9.8 m / s².

Hence, P = 0.008 m x dg = 0.008 m x 13.6 x 10³ kg / m³ x 9.8 m / s² ~ 1066 N / m².

Area of the bottom of the pool = A = 20.8 m x 37.9 m = 788.32 m².

Hence, the force on the bottom of the pool increases by : P x A = 1066 N / m² x 788.32 m² ~ 8.4 x 10⁵ N.