A body is placed on a horizontal plank executing S.H.M. along vertical direction. Its amplitude of oscillation is $3.92 \times 10^{– 3}m$. What should be the minimum periodic time so that the body does not loose contact with the plank?
The body will not loose contact with the surface, $ if mg = m \omega ^2 r = { m4 \pi ^2 \over T^2 } . r $ (where r is amplitude ) $ \therefore T = 2 \pi \sqrt { r \over g} $