1. The problem statement, all variables and given/known data A race car starts from rest and travels east along a straight and level track. For the first 5.0s of the car's motion, the eastward component of the car's velocity is given by vx (t) = (0.920m/s^3) t^2. What is the acceleration of the car when vx = 13.9m/s ? 2. Relevant equations a= Δv/Δt 3. The attempt at a solution I attempted to solve the problem by using the given formula for vx(t) 13.9 = (.92m/s^3)* t^2 With this i solved for t and got 3.89s. so using this I put it in to the formula for a (13.9 - .92)/(3.89-1) = 4.5m/s Unfortunantly this was wrong. can anyone help me? Should I have subtracted 0 for both initial velocity and initial time? or was that general thought process right? Thank you.