One vertical side wall of a glass aquarium is 1 m tall and 2 m wide. With the tank filled to the brim with water, find the total hydrostatic force exerted by the water on this side wall. (Take rho = 1000 kg/m³, g = 9.8 m/s².)

980 * 10³ N
9.8 * 10³ N
0.98 * 10³ N
0.098 * 10³ N

Correct answer: 9.8 * 10³ N

Solution

The gauge pressure varies from 0 at the surface to rho*g*H at the bottom, so the mean pressure on the wall is rho*g*H/2 acting over the wetted area H*width. This gives F = rho*g*H²*width/2 = 1000*9.8*1*1*2/2 = 9.8*10³ N.

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