Question

An object weighs 78 gf in air, 72 gf in water and 70 gf in a liquid. (3)

i. Calculate the relative density of the liquid

ii. How much will the object weigh in a liquid of relative density 0.82?​

Answer 1

According to Archimedes principle,

Upthrust = Weight of liquid displaced

Weight of water displaced = 80-64 = 16

Now, density of water = 1g/cm³

1 g/cm³ = 16 g / x cm³

Therefore, volume of water displaced =

x = 16 cm³

So, volume of the solid = 16 cm³

It density = Mass/volume = 80/16 = 5 g/cm³

Relative density = Density of solid /Density of water = 5/1 = 5

Now, since the solid's density is more than water, it will sink