If a car goes along a straight road heading west and speeds up from 25 ft/s to 60 ft/s in 5 s, calculate the acceleration.

Acceleration  = 

         (change in speed) / (time for the change)
and
         direction of the change.

Change in speed = (end speed)-(start speed) = (60 - 25) = 35 f/s
Time for the change = 5 sec
Direction of the change = west

                 Acceleration  =  7 ft/sec² west .