A mass m = 25 is attached to a unit spring with k = 1, and frictional

Question:

A mass m = 25 is attached to a unit spring with k = 1, and frictional coefficient β = .01. The spring will break when it moves more than 1 unit. Ignoring the effect of the transient, what is the maximum allowable amplitude a of periodic forcing at frequency η =
(a) .19
(b) .2?
(c) .21?