262let the velocity at mean pos. be v m/s
1/2 * k *A2 = 1/2*M*v2 ... (i)
after adding the lump , M' = M+m
from C.O.M ,
Mv =(M+m)v2 ...... (ii)
now new amplitude = A2
1/2*k*A22 = 1/2*(M+m)*v22 ... (iii)
from the above eqns. i) ii) iii) ,
A2 = A √MM+m