The acceleration of a particle executing $SHM$ is

$A$ $0.10\, kg$ block oscillates back and forth along a horizontal surface. Its displacement from the origin is given by: $x = (10\,cm)\cos [(10\,rad/s)\,t + \pi /2\,rad]$. What is the maximum acceleration experienced by the block?

$A$ piston is performing $S.H.M.$ in the vertical direction with a frequency of $0.5 \,Hz$. $A$ block of $10 \,kg$ is placed on the piston. The maximum amplitude of the system such that the block remains in contact with the piston is: (in $\,m$)

The phase difference between the instantaneous velocity and acceleration of a particle executing simple harmonic motion is

$A$ particle moving along the $X$-axis executes simple harmonic motion. The force acting on it is given by: (Where $A$ and $K$ are positive constants)

$A$ particle of mass $0.3 \, kg$ is subjected to a force $F = -kx$ with $k = 15 \, N/m$. What will be its initial acceleration if it is released from a point $20 \, cm$ away from the origin? (in $m/s^2$)