1. The problem statement, all variables and given/known data He is running around a running track training for a 400m race. His velocity is 5.11m/s around the circular end of the track, which has a radius of 31.8m. I'm trying to find his acceleration which I know is 0.821ms-2 but I can't find out how to get it. 2. Relevant equations v=rω d=rθ a=rα ω=θ/t α=ω/t ω=2πf ƒ=1/T 3. The attempt at a solution I first calculated his angular velocity of 0.160rad/s. Then re-arranged d=rθ to θ=d/r and got 12.57rad. Then I re-arranged ω=θ/t to get t=ω/θ and got 0.0127s which I know must be wrong... anyways I then used α=ω/t and got 12.59rads-2 and finally a=rα and I got 400ms-2 and the answer is 0.821ms-2.