Question 169699
the initial velocity is 65m/s and the final velocity is zero, so the average velocity is 32.5m/s


the time to stop is 250m / 32.5m/s or 7.69s


the acceleration is 65m/s / 7.69s or 8.45m/s^2


since the acceleration is opposite to the direction of motion (deceleration), it is NEGATIVE