At 5 seconds, an object's velocity is 9 meters per second. at 8 seconds, the object's velocity is 25 meters per second. assuming a constant acceleration, what is the acceleration in meters per second per second of the object? (if necessary, round to the nearest hundredth.)

Acceleration  =  (change in speed) / (time for the change) .

Change in speed = (25 m/s - 9 m/s) =  16 m/s

Time for the change = (8 sec  -  5 sec)  =  3 seconds

Acceleration  =  (change in speed) / (time for the change)

                       =                 (16 m/s)  /  (3 sec) 

                       =                          (5 and 1/3)  m/s²  .

(rounded to the nearest hundredth ...  5.33 m/s² . )

Igot the answer of 15.8 years.