Question

A car traveling at 40 m/s starts to decelerate steadily. It comes to a complete stop in 5 seconds. What is its acceleration? m/s2

Answer 1

Acceleration =

           (change of speed)  /  (time for the change).

Change of speed = (speed at the end) - (speed at the beginning)

                          =      ( zero )  -  (40 m/s)

                           =        -40 m/s .

Acceleration =  (-40 m/s) / (5 seconds)

                   =    -8 m/s² .