1. The problem statement, all variables and given/known data From t = 0 to t = 5.00 min, a man stands still, and from t = 5.00 min to t = 10.0 min, he walks briskly in a straight line at a constant speed of 2.5 m/s. What is his average acceleration aavg in the interval 2.00 min to 8.00 min? 2. Relevant equations I know that in the formula the A_avg is ∆V/∆t... but I can't make it work for me. It says the answer is .00694 m/s^2, but I keep getting a different answer. 3. The attempt at a solution I tried to calculate the final velocity (V_f): ∆d/∆t: [2.5 m/s x 180 s]/480s. (or 2.5 m/s x 3 minutes)/8 minutes). This give me 0.975 m/s^2. The initial velocity (V_i) seems to me that it would be 0 at t=2 minutes. So A = [.975-0]/∆t = [.975 m/s]/360s = .0027 m/s^2. but this is wrong. Help please. where did I mess up?