Question

Two trains each 125 m
long are travelling in opposite direction with velocity 10m/s and 15m/s the time of crossing is
(please answer it fast )​

Answer 1

Answer:

$\sf{The \ time \ of \ crossing \ will \ be \ 10 \ seconds.}$

Given:

• Two trains each 125 m long are travelling in opposite direction with velocity 10 m/s and 15 m/s

To find :

• The time of crossing.

Solution:

$\sf{Here, \ Distance=Sum \ of \ length \ of \ trains.}$

$\sf{\therefore{Distance=2\times125}}$

$\sf{\therefore{Distance=250 \ m}}$

______________________________

$\sf{\underline{\underline{Concept:}}}$

$\sf{If \ a \ body \ move \ with \ some \ velocity, \ we \ can}$

$\sf{also \ say \ that \ it's \ surrounding \ is \ moving}$

$\sf{opposite \ to \ it \ and \ body \ is \ stationary. }$

______________________________

$\sf{Let \ the \ train \ moving \ with \ velocity \ 10 \ m \ s^{-1}}$

$\sf{be \ stationary, \ so \ the \ speed \ of \ objects}$

$\sf{moving \ opposite \ to \ the \ train \ will \ increase}$

$\sf{by \ 10 \ m \ s^{-1}}$

$\sf{Hence, \ the \ speed \ of \ second \ train \ will}$

$\sf{be \ now \ 15+10=25 \ m \ s^{-1}}$

$\sf{Here,}$

$\sf{Distance=250 \ m \ and \ Speed=25 \ m \ s^{-1}}$

$\boxed{\sf{Time=\dfrac{Distance}{Speed}}}$

$\sf{\therefore{Time=\dfrac{250}{25}=10 \ s}}$

$\sf\purple{\tt{\therefore{The \ time \ of \ crossing \ will \ be \ 10 \ seconds.}}}$