chuk-chuk -chuk-chuk rail gaadi

Number Theory Level 3

A train 270 m long is moving at a speed of 24kmph. It will cross a man coming form the Opposite direction at a speed of 3kmph, in seconds

46 24 36 40

1 solution

Aniket Verma
Mar 5, 2015

Velocity of train $= \dfrac{24\times 5}{18}$ $ms^{-1}$

velocity of man $= \dfrac{3\times 5}{18}$ $ms^{-1}$

relative velocity of train with respect to man $= \dfrac{27\times 5}{18} = \dfrac{15}{2}$ $ms^{-1}$

let time taken by train to cross the be $t$

therefore $\dfrac{15t}{2} = 270$

hence $t = \dfrac{270\times 2}{15} = 36$ $s$