Is it true that a floating object will be in stable equilibrium only if its center of buoyancy lies above its center of gravity? Illustrate with examples.

Radhika Batra Grade: 11

        Is it true that a floating object will be in stable equilibrium only if its center of buoyancy lies above its center of gravity? Illustrate with examples.

4 years ago

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Kevin Nash

askIITians Faculty

332 Points

							No, it is not true that a floating object will not be in stable equilibrium only if the center of buoyancy lies above its center of gravity.
Consider an object flats in a pond.
For stable equilibrium, the buoyant force (F_b) which acts towards the center of buoyancy (B) and the weight (W) of the object acts towards the center of gravity (G) should lie on the same vertical axis. This is shown below:


When the center of gravity lies above the center of buoyancy but not on the same vertical axis, a net torque acts on the object. Thus, the object will be in unstable equilibrium.

The above example shows that the object is not in stable equilibrium when the center of gravity lies above the center of buoyancy. But both the center should lie on the same vertical axis of the object.