I have 3 separate cases of an object decelerating at different rates. The aim is to find the acceleration for each case. Case 1 Initial velocity: 1.663m/s Displacement: 0.12m Time: 0.139s Case 2 Initial velocity: 1.663m/s Displacement: 0.12m Time: 0.155s Case 3 Initial Velocity: 1.663m/s Displacement: 0.12m Time: 0.24s The attempt at a solution Simply using the equations of linear motion (s=ut+1/2at^2) I got the following results: Case 1: -11.5063m/s^2 Case 2: -11.4685m/s^2 Case 3: -9.69167m/s^2 Why? I expected the magnitude of deceleration to increase from case 1 to case 3 Also deceleration of 11m/s^2 seems excessively high. I need to understand this for an assignment due in a few days. I've done this many times now and with different methods such as finding the final velocity first and then finding the acceleration but every method gives me the same results or at least the same pattern of the deceleration decreasing.