Question

A stone of density 3000kgm3 is lying submerged in water of density 1000kgm3.If the mass of the stone in air is 150 kg, calculate the force required to lift the stone.

Answer 1

Given the details, the volume of the stone is 0.05m³. When in water, due to the upthrust, the apparent density will be 3000-1000=2000kg/m³.
Thus, while in water, the force required to lift the stone will be 0.05*2000=100kgf