In damped $SHM$,the $SI$ unit of damping constant is

Why is absolutely pure simple harmonic motion not possible?

$A$ spring-mass system executes damped harmonic oscillations given by the equation $y = A e^{-\frac{bt}{2m}} \sin(\omega' t + \phi)$,where the symbols have their usual meanings. If a $2 \ kg$ mass $(m)$ is attached to a spring of force constant $(K) = 1250 \ N/m$,the period of the oscillation is $(\pi / 12) \ s$. The damping constant $b$ has the value ..... $kg/s$.

The amplitude of a simple pendulum,oscillating in air with a small spherical bob,decreases from $10 \ cm$ to $8 \ cm$ in $40 \ s$. Assuming that Stokes' law is valid,and the ratio of the coefficient of viscosity of air to that of carbon dioxide is $1.3$. The time in which the amplitude of this pendulum will reduce from $10 \ cm$ to $5 \ cm$ in carbon dioxide will be close to ..... $s$ $(\ln 5 = 1.601, \ln 2 = 0.693)$

If velocity is not large,then on which factor does the damping force on an oscillator in a medium depend?

What is the amplitude of a damped oscillator if time becomes $t = 2m$?