On a smooth inclined plane a block of mass $M$ is fixed to two rigid supports using two springs as shown in the figure. If each spring has spring constant $k$, then the period of oscillation of the block is

(Neglect the masses of the springs)

If the displacement of a particle executing simple harmonic motion is given by $x=0.5 \cos (125.6 t)$, then the time period of oscillation of the particle is nearly (Here, $x$ is displacement in metre and $t$ is time in second)

The amplitude of a damped harmonic oscilator becomes $50 \%$ of its initial value in a time of 12 s . If the amplitude of the oscillator at a time of 36 s is $x \%$ of its initial amplitude, then the value of $x$ is

A particle is executing simple harmonic motion with amplitude $A$. The ratio of the kinetic energies of the particle when it is at displacements of $\frac{A}{4}$ and $\frac{A}{2}$ from the mean position is