Hi,

I am kinda having trouble with the following problem:

Suppose that the acceleration of a model rocket is proportional to the difference between 120 ft/sec and the rocket's velocity. If it is initially at rest and its initial acceleration is 120 ft/sec^2, how long will it take to accelerate to 96 ft/s?

t= ______________ sec

What I have tried:

dv/dt=k(120-v)

integrating both sides:

-ln|120-v| = t + C

Since, t = 0 and initial velocity v = 0

Thus, C = -ln|120|

I am stuck here:

Please help,

Many thanks....