Basically what I want to do is the opposite of finding average velocity from constant acceleration. I want to know how to find the minimum possible acceleration where the average velocity v is known and the distance d is know. The acceleration is assumed to be constant. For for example, a ship in outer space departs from position a and arrives at position b in a straight line. We know the departing and arriving time, and we know the distance, so we know the average velocity. The ship accelerated to the half way point and then decelerated until it stopped at it's destination. The acceleration and deceleration has a constant rate. Initial and final velocities at positions a and b are zero. How do we find the rate of acceleration?