A wire is suspended vertically from a rigid support. When loaded with a weight in air, the wire extends by `16cm`. When the weight is completely immersed in Water, the extension is reduced to `14 cm`. The relative density of the material of the weight is

Options

A. `2gcm^-3`
B. `6gcm^-3`
C. `8gcm^-3`
D. `16gcm^-3`

Answer

C

Explanation

`Y=(Fl)/(atrianglel)`,`Y`, `l` and `a` are constants
`Fpropl`
in the first case `Vrhogprop16`
In the second case,
`(rhog-Vxx1xxg)prop14`
Dividing, `(Vg(rho-1))/(Vgrho)=(14)/(18)=(7)/(8)`
or `(rho-1)/(rho)=(7)/(8)` or `8rho-7rho` or `rho=8gcm^-3`