How long did the car decelerate to a complete stop if its initial speed was 72 km / h

How long did the car decelerate to a complete stop if its initial speed was 72 km / h and the acceleration during braking was 5 m / s2

To find out the duration of braking of the specified car, we apply the formula (we take into account that the movement of the specified car is slowed down): V = V0 – a * t = 0 (complete stop), from where we express: t = -V0 / (-a) = V0 / a.

Data: V0 – initial speed (V0 = 72 km / h, which is 20 m / s in SI); a – acceleration during deceleration (a = 5 m / s2).

Let’s perform the calculation: t = V0 / a = 20/5 = 4 s.

Answer: The braking of the specified vehicle should have lasted 4 seconds.