A uniform disc of radius r is to be suspended through a small hole made in the disc. Find the minimum possible time period of the disc for small oscillations. What should be the distance of the hole from the centre for it to have minimum time period?

Answer

B

Explanation

Let mass of uniform disc =m
Then minimum time period
`T=2pi sqrt(1/(mg.sqrt2r))`
`=2pi sqrt((2mr^2)/(sqrt2 mgr))`
`=2pi sqrt(2r^2)/g)`
clearlyl for minimum time period distance of hole from the centre `=r/sqrt2`.