A body is attached to the lower end of a vertical spiral spring and it is gradually lowered to its equilibrium position. This stretches the spring by a length x. If the same body attached to the same spring is allowed to fall suddenly, what would be the maximum stretching in this case
When spring is gradually lowered to it's equilibrium position
kx=mg∴x=mgk.
When spring is allowed to fall suddenly it oscillates about it's mean position
Let y is the maximum elongation, then at lower extreme, by the conservation of energy
⇒12ky2=mgy⇒y=2mgk=2x.