# If an object with uniform acceleration (or deceleration) has a speed of 1 m/s at t=0 and moves a total of 180 m by t=4, what was the object's rate of acceleration?

$22 {\text{ ms}}^{-} 2$
The average speed of the particle over 4 s is {180 " m"}/{4 " s"} = 45 "m"/"s".
Since for a uniformly moving object the average speed over an interval is the average of the initial and final speeds, the final speed must be $= 2 \times 45 \text{m"/"s" - 1 "m"/"s" = 89 "m"/"s}$.
Thus, the acceleration is (89 " ms"^-1 - 1" ms"^-1)/{4" s"}=22 " ms"^-2