Question

A car starts from rest , then accelerates at 1.20 m/s^2 fo 7.00 s. It hits the brakes, slowing to a stop at a rate of -4.25 m/s^2. What is the total distance travelled?

Answer 1

In the first 7.00 seconds, the car travels a distance of

1/2 (1.20 m/s²) (7.00 s)² = 29.4 m

and after this time it will have reached a speed of

(1.20 m/s²) (7.00 s) = 8.40 m/s

Afterwards, the car slows to a stop under uniform acceleration, so that

0² - (8.40 m/s)² = 2 (-4.25 m/s²) x

where x is the distance traveled in the time it takes for the vehicle to stop. Solve for x :

x = (8.40 m/s)² / (2 (4.25 m/s²)) ≈ 8.30 m

So, the total distance traveled is approximately 29.4 m + 8.30 m ≈ 37.7 m.