Question

Why is the gravity bulb of a commercial hydrometer for heavier liquids made heavy?

Answer 1

1. Centre of gravity of a body helps us to predict the stability of a body against overturning or tilting.
2. Lower the centre of gravity of a body, the more stable is the body against overturning or tilting.
3. Higher the meta-centre of a floating body, the more stable is the body against overturning or tilting.
4. For stable equilibrium of a floating body, meta-centre must be above the centre of gravity of the body.
5. The bulb of the hydrometer for heavier liquids is made bigger and heavier to lower the centre of gravity of the bulb of the hydrometer.
6. This ensures that the meta-centre will lie above the centre of gravity and the bulb floats upright in stable equilibrium.
7. The gravity bulb is generally filled with lead shots of high density which lower the centre of gravity of the hydrometer.

Hence, the gravity bulb of a commercial hydrometer for heavier liquids is made heavier to ensure that the bulb floats upright and there is no tilting of the hydrometer.