A pendulum has time period `T` in air when it is made to oscillate in water it acquired a time period `T = sqrt(2)T` The density of the pendulum bob is equal to (density) of water `= 1)`

Explanation

The effective acceleration of a bob in water =g.
`=g(1-d/D)`, where d and D are the density of water and the bob respectively. `D/d=` specific gravity of the bob. Since the period of oscillation of the bon in air and watrer are given as
`T=2pi sqrt(l/g)` and `T.=2pisqrt(l/(g.))`
`:.T//T.=sqrt((g.)/g)=sqrt((g(1-d//D))/g)=sqrt(1-d/D)=sqrt(1-1/s)`
putting `T//t.=1//sqrt(2)`, we obtain
`1/2=1-1/2`
`implies1/s=1/2impliess=2`