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 weighing 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 m s–2.)

Question

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 weighing 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 m s–2.)

MyClass24 · Accepted Answer

Buoyant force, F = Vpg

p= Density of water, V = Volume of water displaced by the body
Volume and density of an object decides its Buoyancy. Cube will experience a greater byoyancy in saturated solution. If cube is reduces to 4 cm on each side, volume of cube becomes less as the buoyancy will be reduced as buoyant force is directly proportional to volume.
(ii) The magnitude of the buoyant force given by F = Vpg
where V = Volume of body immersed in water or volume of water displaced, p = Density of liquid. [&there4; Given, mass of a ball = 4 kg, density = 4000 kgm-3].
Hence Volume of solid = 𝑀𝑎𝑠𝑠
𝐷𝑒𝑛𝑠𝑖𝑡𝑦
= 4
4000
= 1
1000
Buoyancy F= Vpg
== 1
1000
10N
x 1000x10