Answer :
Acceleration = (change in speed) / (time for the change)
Change in speed = (25 - 15) = 10 m/s
Time = 15 s
Acceleration = 10/15 = 2/3 m/s
Change in speed = (25 - 15) = 10 m/s
Time = 15 s
Acceleration = 10/15 = 2/3 m/s