1. The problem statement, all variables and given/known data Starting from rest, a wheel has constant α = 3.0 rad/s2. During a certain 4.0 s interval, it turns through 120 rad. How much time did it take to reach that 4.0 s interval? ω0 = 0 α = 3.0 rad/s2 θf = 120 rad 2. Relevant equations Δθ = ω0⋅t + ½αt2 3. The attempt at a solution 120 rad = (1/2)(3.0 rad/s2)(t2) Solving for t: t = [2(120 rad) / (3.0 rad/s^2)]½ t = 8.49 s Subtracting 4.0 s to the said time leads to my final answer, 4.9 s The book says that the answer should be 8.0 s.