I Need Help Clearing For B On An Equation

[leomarrg]

Consider the movement of the mass and spring with friction

A * [e ^ - (b / 2m) t] * cos (sqrt (k / m - (b / 2m) ^ 2)) t + φ)

With A = 2m, k = 3N / m, m = 5Kg and φ = 0, we could change to the value of "b" from zero until the oscillations disappear for the first time and the function does not change to negative values. In this case, the friction now has a very noticeable effect: it lengthens the period of the oscillation so much that no oscillations will be seen (T -> infinity).

The theory indicates when that should happen. Clear for b from the equation and record the predicted value for b = .... (Kg / s) (at least two decimal places to the right of the point)

The question is complete, the exercise is clear for b, I don't get how to do it. The answer is 7.746

Edited February 26, 2020 by leomarrg