Question

A car is travelling at 60 km /h overtakes another car travelling at 42 km/h .assuming each car to be 5m long ,find the time taken during the overtake

Answer 1

Here,

Speed of the first car = 60 km/h

Speed of second car= 42 km/h

So, the relative speed of first car with respect to second car = 60-42 =18 km/h

To convert km/h to m/s we multiply the Speed in km/h by 5/18 .

So, relative speed = 18 × (5/18) = 5 m/s.

Now, as the first car overtakes the second car, it has to cover the second car's length as well it's own length. Understand it : the front part of the first car will first cover the length of second car and then the rear part of first car will cover the length of second car.

Thus, in order to overtake, the first car covers a distance = 5+5 = 10m

So, time taken = (10/5) second = 2 second.

Now, in order to calculate road distance, time remains same in every frame in this case. Thus, the total road distance covered by first car = (Speed of 1st car)×(time taken in overtake) = (60 x (5/18))×2 m = 33.3 m

Hope it helps !