Q.

Two non-mixing liquids of densities ρ and nρ (n>1) are put in a container. The height of each liquid is h. A solid cylinder of length L and density d is put in this container. The cylinder floats with its axis vertical and length pL (p<1) in the denser liquid. The density d is equal to           [2016]
 

1 {2+(n-1)p}ρ  
2 {1+(n-1)p}ρ  
3 {1+(n+1)p}ρ  
4 {2+(n+1)p}ρ  

Ans.

(2)

A = area of cross-section of cylinder

Using law of floatation,

weight of cylinder=upthrust by two liquids

L×A×d×g=nρ×(pL×A)g+ρ(L-pL)Ag

         d=npρ+ρ(1-p)=(np+1-p)ρ

         d={1+(n-1)p}ρ