Acar is rolling backward when it hits the gas. after 8.25 s it is moving forward at 8.62m/s, and is 12.9m to the right of its starting pount. what was its starting velocity ?

Explanation:

The given data is as follows.

        Final velocity (v) = 8.62 m/s,         Initial velocity () = ?

         time = 8.25 sec,          distance (s) = 12.9 m

Hence, formula to calculate the initial velocity is as follows.

                   v =

                 8.62 m/s =

                = 8.62 m/s - 8.25a ......... (1)

Also,   s = ...... (2)

Therefore, substitute the value of from equation (1) into equation (2) as follows.

                s =

               s = ....... (3)  

Now, putting the values of s and t into equation (3) as follows.

         s =  

        12.9 m =  

               a = 1.71  

Therefore, using equation (1) the value of initial velocity will be as follows.

                      =

                              =

                              = -5.49 m/s

Thus, we can conclude that starting velocity of the car is -5.49 m/s.