The Distance the car is moving at that time?

Question

A car that weighs 12700.0 N is initially moving at a speed of 35.0 km/hr when the brakes are applied and the car is brought to a stop in 4.8 s. Find the magnitude of the force that stops the car, assuming it is constant.
I found the magnitude to be 2.62 X 10^3 N and now it's asking for the distance the car moved?

Answer 1

distance = avg. speed x time

In this problem the acceleration is constant so the speed is changing steadily. In such a case:

avg. speed = (initial_speed + final_speed) / 2

So:

distance = ((initial_speed + final_speed) / 2) x time