Question

At 20 ° C a mineral solid in the air weighed 482.5 g and 453.8 g when immersed in water.

1)Calculate the absolute density and relative density in water.

2)If the density of benzene, at that temperature is 0.879 g / ml. Calculate the weight of the mineral when immersed in benzene

Answer 1

1) If mass of an object in air be m and that in a fluid be m', then relative density is given by

Buoyant force on an object immersed in a fluid is given by the difference in it's real weight and apparent weight.

So, Buoyant force on the solid is

If the volume of the solid be V and the density of the fluid be then we can say,

g is the acceleration due to gravity.

Putting the values,

Hence, absolute density of the object is

2) As we found out volume of the solid is

So, Buoyant force when the solid is immersed in benzene is

is the density of Benzene which is given by

Putting the values,

So, if real weight of the solid in air be W, apparent weight W' of the solid in benzene is

So, mass of the solid when immersed in benzene is

This is the weight of the solid when immersed in Benzene.