A particle of mass 0.02 kg executes S.H.M. about $\mathrm{x}=0$ under the influence of a force as shown in figure. The period of S.H.M. is

Two (A and B) pendulums begin to swing simultaneously. The first pendulum (A) makes five oscillations when the other (B) makes three oscillations. The ratio of the lengths of pendulum $A$ to that of $B$ is

A particle performs S.H.M. with amplitude 'A'. The speed of the particle is $\left(\frac{1}{3}\right)^{\text {rd }}$ of the maximum speed when its displacement from the mean position is

A particle vibrating simple harmonically has an acceleration of $16 \mathrm{~cm} / \mathrm{s}^2$, when it is at a distance of 4 cm from the mean position. Its periodic time is