
Damped Spring Question
Here is the question:
A spring with a 7kg mass and a damping constant 5 can be held stretched 1 meters beyond its natural length by a force of 4 newtons. Suppose the spring is stretched 2 meters below springmass equilibrium and then released with zero velocity.
Find the position of the mass after t seconds.
Here are the data:
m = 7 kg
c = 5
k = 4/1 = 4
c^2  4mk = 87 (Underdamped)
Using the formula:
w = sqrt(4mk  c^2)/2m
= sqrt(87)/14
x = e^(c/2m)t(C1Cos(wt) + C2Sin(wt))
and I think the initial values are:
x(0) = 2 x'(0) = 0
so I got
x(t) = e^(5/14)t(2Cos(sqrt(87)/14*t))
But it's wrong!!
Please help!!