Mechanical Properties Of Fluids Ques 13

13. Two non-mixing liquids of densities $\rho$ and $n \rho$ $(n>1)$ 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 :

(a) $\{1+(n+1) p\} \rho$

(b) $\{2+(n+1) p\} \rho$

(c) $\{2+(n-1) p\} \rho$

(d) $\{1+(n-1) p\} \rho$

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Answer:

Correct Answer: 13.(d)

Solution:

  1. (d) As we know, Pressure $P=Vdg$

Here, $L A d g=(p L) A(n \rho) g+(1-p) L A \rho g$

$\Rightarrow d=(1-p) \rho+pn \rho=[1+(n-1) p] \rho$

When a body of volume $V$ floats in a liquid then

Weight of the body $=$ up thrust

$\Rightarrow V \rho g=Vin \sigma g$

Here, $V=$ volume of body

$\rho=$ density of body

$\sigma=$ density of liquid

$V _{\text{in }}=$ volume of the body immersed in liquid