Question

Pavel took an earthen pot which was filled with water up to its brim. The earthen pot was conical in shape and kept with its apex in downward direction.

1. If the vertical height of the earthen pot is 12 cm, where does its centre of gravity lie?
2. Pavel poured out all the water from the pot. How will its centre of gravity shift – towards the open end or towards its apex?
3. Pavel wanted to grow a plant in the given pot. So, he filled it completely again with some soil. What will be the new position of its centre of gravity?

Answer 1

1. For a uniformly filled cone, the centre of gravity lies on its axis, one-quarter of the height from its broad base. Here this is 12 ÷ 4 = 3 cm from the open end.
2. When the water is removed, the centre of gravity shifts towards the apex. The remaining earthen pot has more of its material near the open end than near the pointed end.
3. When the pot is completely filled with soil, the centre of gravity of the soil lies on the axis, 3 cm from the open end. The exact centre of gravity of the pot and soil together depends on their relative masses.