What is the force constant of a particle executing $SHM$?

The variation of displacement with time of a simple harmonic motion $(SHM)$ for a particle of mass $m$ is represented by $y = 2 \sin \left(\frac{\pi t}{2} + \phi\right) \text{ cm}$. The maximum acceleration of the particle is

$A$ body oscillates with $S.H.M.$ according to the equation $x = (5.0 \, m) \cos [(2 \pi \, rad \, s^{-1}) t + \pi / 4]$. At $t = 1.5 \, s$,its acceleration is ....... $m / s^2$.

Under the action of a force $F = -75 y$, where $F$ is in Newton and $y$ is in meters, an object of mass $3 \,kg$ executes simple harmonic motion. If the velocity of the object at the mean position is $2.5 \,ms^{-1}$, the maximum acceleration of the object is (in $\,ms^{-2}$)

The acceleration $a$ of a particle undergoing $S.H.M.$ is shown in the figure. Which of the labelled points corresponds to the particle being at $-x_{max}$?

The maximum force acting on a particle executing simple harmonic motion is $10 \,N$. The force on the particle when it is midway between mean and extreme positions will be