1. The problem statement, all variables and given/known data A particle travels from point A to point B following a semicircular path (a half-circle) of radius 5 m, and it travels at a constant speed of 1 m/s. Find the average acceleration of the particle. 2. Relevant equations Average acceleration = change in velocity/ change in time Total time = distance / speed 3. The attempt at a solution I already know the answer, and I understand why it's true: v0 = 1 m/s vf = -1 m/s total time = (5 pi m) / (1 m/s) = 5pi seconds Avg acceleration = (2 / (5pi) ) m/s^2 My question is: Is the average acceleration ever equal to the (average velocity/ time) ? In this case, I know it's not because: Avg velocity = displacement / time = 10 m / 5pi sec = (2/ pi) m/s And, if I divided by the time, I would get a factor of pi^2 in the denominator, which is not in my original answer. I would really appreciate any help sorting this out!