Question

Two trains, each $50m$ long, are travelling in opposite directions with velocity $10m/s$ and $15m/s$. The time of crossing is-

• A. $2s$
• B. $4s$
• C. $2\sqrt{3}s$
• D. $4\sqrt{3}s$

Answer 1

The correct option is B $4s$

Velocity of one train w.r.t. other $V_{rel}=10+15=25m/s$

Distance covered to cross $D_{rel}=50+50=100m$

Time taken $t=\frac{100}{25}=4s$