Hydrostatics involves the study of bodies which are subjected to forces due to fluids which are at rest. These forces include those due to weight, fluid pressures and buoyancy.

Sample problem: Masses floating in water

A wooden cube of side h m, volume V m3 and mass M1 kg floats in water with one quarter above the surface. If another wooden cube of mass M2 kg is placed on top of the wooden cube, it will sink until its top is level with the surface of the water. Find M2 in terms of M1. (Assume density of water = r = 1,000 kg/m3)


The physical model of the floating masses is illustrated in Fig. 1.

The forces acting on the physical model are shown in Fig. 2.

Mass M1:

The forces acting are shown in Fig. 2:

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