The spring has a length l. Whem m is placed over it, the equilibrium position becomes O′ . If it is pressed from O′ (the equilibrium position) to O",O′O" is the amplitude. ∴OO′=
mg
k
=
2×10
200
=0.10m mg=kx0 If the restoring force mAω2>mg, then the mass will move up with acceleration, detached from the pan. i.e., A>gk∕m⇒A>
20
200
>0.10m The amplitude >10cm. i.e. the minimum is just greater than 10cm. (The actual compression will include x0 also. But when talking of amplitude, it is always from the equilibrium position with respect to which the mass is oscillating.