Question

A sports car passing a police check post at 60${kmh}^{ - 1}$ immediately started slowing down uniformly until its speed was 40${kmh}^{ - 1}$. It continued to move at this speed until it was passed by a police car 1 km from the check post. The police car had started from rest from the check post at the same instant as the sports car had passed the check post. The police car had moved with constant acceleration until it had passed the sports car. Assuming the time taken by the sports car in slowing down from 60${kmh}^{ - 1}$ to 40${kmh}^{ - 1}$ was equal to the time it travelled at constant speed before passed by the police car, find the time measured from the check post when the speeds of the two cars were equal.​

Answer 1

Answer:

A sports car passing a police check post at

immediately started slowing down uniformly until its speed was

. It continued to move at the same speed until it was passed by a police car

from the check post. The police car had started from resta t the check post at the same instant as the speorts car had passed the chstant as the sports car had passed the check post. The police car had moved with a constant acceleraation until it had passed sports car. Assuming that the time taken by the sports car in slowing down from

to

was equal to the time that it travelled at constant speed before passed by the police car, find <br> (a) the time taken by the police car to reach the sports car, (b) the speed of the police car at the instant when it passed the sports caar, (c ) the time measured from the check post when the speeds of the two cars wer equal.