A spring with one end attached to a mass and the other to a rigid support is stretched and released. When is the magnitude of acceleration a maximum?

Explanation

Maximum restoring force setup in the spring when stretched by a distance `r` is F=-kr
Potential energy of stretched spring =`1/2kx^2`
As `F prop r` and this force is directed towards equilibrium position, hence if mass is left free, it will execute damped SHM due to gravity pull.
Maximum of acceleration in the mass attached to one end of spring when just released is
`a=F/m=(-k)/mr=`(Maximum)
`therefore` The magnitude of acceleration of the spring will be maximum, when just released.