question_answer 59)

  (i) 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. (ii) A ball weighing 4 kg of density 4000  is completely immersed in water of density . Find the force of buoyancy on it. (Given, )  

Answer:

  (i) Buoyant force, (where, = Density of water, V = Volume of water displaced by the body) Buoyant force depends upon volume and density, since, saturated salt solution have higher density than the water. So, in saturated solution, cube will experience a greater buoyant force. If each side of the cube is reduced to 4 cm, then the volume of cube become less. As buoyant force is directly proportional to the volume. So, buoyant force will be less than as compared to the first case for water. (ii) The magnitude of the buoyant force given by where V = Volume of body immersed in water or volume of water displaced,  = Density of liquid. [ Given, mass of a ball = 4 kg, density] Volume of solid                                 Buoyancy,