1. The problem statement, all variables and given/known data Velocity in m/s at time t is defined as v= 20t(1+2t)^-2 Find Acceleration at 0.5s 2. The attempt at a solution I missed the day we covered this topic in class and I am under the assumption that I would find the derivative of 20t(1+2t)^-2 and then find the derivative once more to get acceleration. Once I get the second derivative its as easy as substituting 0.5 for t. Unfortunately I never get the correct answer which I was told is 9.6m/s. Is the answer wrong? I end up with 15m/s all the time.