a solid weighs 30gf in air and 26gf when completely immersed in a liquid of relative density 0.8. find (1)the volume of solid and(2)the relative density of solid.

Asked by mansi | 28th Feb, 2015, 07:41: PM

Expert Answer:

Let V be the volume of the solid.
Given relative density of the liquid =0.8
Weight of the solid in air = 30 gf
Weigth of the solid in liquid = 26 gf
We know that the loss in weight of the solid when immersed in liquid = The weight of the liquid displaced.  ----------(1)
Weight of the liquid displaced = Volume of the liquid displaced × Relative density of the liquid
  = V × 0.8   -----------------------(2)
(2) in (1) gives:
Loss in weight of the solid when immersed in liquid = 0.8 V  ----(3)
Loss in weight of the solid when immersed in liquid = (30 -26)gf = 4 gf   
Substituting in (3) we get:
4 = 0.8 V
i.e V =4 /0.8 = 5 cm3
(1) Therefore the volume of the solid  = 5 cm3
Density of the solid = Mass / volume
 = 30 gf / 5 cm3
 =6 g/cm3
(2) Relative density of the solid =Density of the solid / Density of water
 = (6 g /cm3) /(1 g /cm3)
 = 6 g/cm3
Relative density of the solid = 6 g/cm3
 

Answered by Jyothi Nair | 1st Mar, 2015, 11:39: AM

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