Question

a body of density 0.8g/cm3 will have .. of its volume immersed in water
20,80,40,60​

Answer 1

According to Archimedes' principle.

Mass of volume displaced is by object is buoyancy force.

Let the volume of wood is V.

then the volume submerged in liquid is V/4

let the density of wood be ρ.

let the density of liquid be ρl=0.8cm−3.

weight of wood ρVg.  

buoyancy force =4ρlVg

now weight of block is equal to  buoyancy force.

ρVg=4ρlVg

So ρ=40.8=.2gcm−3

 

then the volume submerged in oil is 60% of is 3V/5

weight of wood ρVg  

buoyancy force =5ρoil3Vg

now weight of block is equal to  buoyancy force.

ρVg=5ρoil3Vg

So ρoil=3ρ×5=30.2×5=0.33gcm−3

Answer 2

According to Archimedes' principle.

Mass of volume displaced is by object is buoyancy force.

Let the volume of wood is V.

then the volume submerged in liquid is V/4

let the density of wood be ρ.

let the density of liquid be ρl=0.8cm−3.

weight of wood ρVg.  

buoyancy force =4ρlVg

now weight of block is equal to  buoyancy force.

ρVg=4ρlVg

So ρ=40.8=.2gcm−3

 

then the volume submerged in oil is 60% of is 3V/5

weight of wood ρVg  

buoyancy force =5ρoil3Vg

now weight of block is equal to  buoyancy force.

ρVg=5ρoil3Vg

So ρoil=3ρ×5=30.2×5=0.33gcm−3