CBSE - Physics - Gravitation

(a) A cube of side 5 cm is immersed in water and then in saturated salt solution. In which case, will it experience a greater buoyant force. If each side of the cube is reduced to 4 cm and then immersed in water, what will be the effect on the buoyant force experienced by the cube as compared to the first case for water. Give reason for each case.
(b) A ball weight 4 kg of density 4000 kg m^-3 is completely immersed in water of density 10³ kg m^-3. Find the force of buoyancy on it. (Given g = 10 ms^-2.)

Ans. (a) (i) The cube will experience a greater buoyant force in the saturated salt solution because the density of the salt solution is greater than that of water.
(ii) The smaller cube will experience lesser buoyant force as its volume is lesser than the initial cube.
(b) Buoyant force = weight of the liquid displaced
= density of water � volume of water displaced �g