Is a 1.8T a good car?

At what time T does the car begin to decelerate?

• The distance s (in feet) covered by a car t sec after starting is given by the following function: s in feet s= -t^3 + 10t^2 + 18t s''(t) = -6t + 20 What time in seconds does the car in seconds begin to decelerate.

• Answer:

  answer is =3.3 sec after acceleration decreases because at 3.3 acceleration is zero