Question

Two trains one travelling at 15 ${ms}^{-1}$ and other at 20 ${ms}^{-1}$ are headed towards one another a straight track. Both the drivers apply brakes simultaneously when they are 500m apart. If each train has a retardation of 1 ${ms}^{-1}$ the separation after they stop is

• A. 192. 5m
• B. 225 .5 m
• C. 187 .5 m
• D. 155.5 m

Answer 1

The correct option is C 187 .5 m

using equations of stopping distance$,$ after applying break train with velocity $15$ travels distance $\frac{{\left(15\right)}^2}{\left(2\right)\left(1\right)}=112.5m$

Similarly$,$ another train travels distance $\frac{{\left(20\right)}^2}{\left(2\right)\left(1\right)}=200m$

So$,$ final separation $500-(112.5+200)=187.5m$

Hence,

option $\left(C\right)$ is correct answer.