Question

7. The driver of a train A moving at a speed of 30 ms sights another train B moving on the same
track at a speed of 10 ms in the same direction. He immediately applies brakes and achieves a
uniform retardation of 2 ms. To avoid collision, what must be the minimum distance between
the trains?​

Answer 1

Answer: 100 m

Explanation:

The relative speed between the two trains is :

30 - 10 = 20m/s

This is the initial relative speed.

When brakes are applied the train slows down.

Given the acceleration = 2 m/s²

u = 20 m/s

With time the train comes to a sudden stop making the velocity 0.

V² = U² - 2as

0 = 400 - 4s

400 = 4s

S = 100m

Answer 2

The relative velocity between the two trains is :

30 - 10 = 20m/s

This is the initial relative speed.

When brakes are applied the train slows down. And to find minimum distance we have to put v= 0 for train A.

also given that the acceleration = 2 m/s²

since, u = 20 m/s

Hence,

V² = U² - 2as

0 = 400 - 4s

s = (400/4)m

S = 100m