Dampening force - find decrease in amplitude

[JoeyBob]

Homework Statement

see attached

Relevant Equations

w=sqrt((k/m)-(b/(2m))^2)

Amplitude = (Amax)e^((-b/(2m)t)

So first I tried to find b.

0.454=(0.6)e^((-b/(2*11.6)*50)

Anyways with some natural log algebra etc. I get b = 0.129378

But when I plug this into the same equation only changing mass to 17.7 kg I get 0.4998 or 50% when the answer should be 59.6%?

 

[TSny]

Amplitude = (Amax)e^((-b/(2m)t)

0.454=(0.6)e^((-b/(2*11.6)*50)

The amplitude decreases to 45.4% of its initial value. So, the final amplitude is not .454