MHTCET 2016 Physics Solved Paper

(a) Time period of simple pendulum in water (T) is given by
T=2π√

l

geff

[geff = acceleration due to gravity in water]
Effective value of acceleration due to gravity when bob is immersed in water, is given by
As weknow, geff = g (

σ−ρ

σ

)
[Here, σ = density of bob, ρ = density of water]
=9.8(

9 8 ×103−103

9 8 ×103

)
= 9.8(

9 8 −1

9 8

) = 9.8 (

1

8

×

8

9

)=

9.8

9

So, T1=2π√

l×9

9.8

⇒ T1=3T [∵T=2π√

l

g

]