Q: Two trains one travelling at 54 kmph and the other at 72 kmph are headed towards one another along a straight track. When they are 1/2 km apart, both derives simultaneously see the other train and apply their brakes. If each train is decelerated at the rate of 1 m-s2, will there be a collision ?

**Click to See Answer : **

$\large S_1 = \frac{u^2}{2a} = \frac{225}{2 \times 1} $

S_{1} = 112.5 m

Velocity of the second train is 72 kmph = 20 m/s

Distance travelled by the second train before coming to rest

$\large S_2 = \frac{u^2}{2a} = \frac{400}{2 \times 1} $

S_{2} = 200 m

Total distance travelled by the two trains before coming to rest

S = S_{1} + S_{2}

= 112.5 + 200 = 312.5 m

Because the greater than 312.5 m, there will be no collision between the two trains.