Discussion Forum

Two trains 140 m and 160 m long run at the speed of 60 km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The time (in seconds) which they take to cross each other, is :

Answer:

Explanation:

Relative speed $=(60+40)$ km/hr $=\left(100\times\frac{5}{18}\right)$ m/sec $=\left(\frac{250}{9}\right)$ m/sec.

Distance covered in crossing each other $=(140+160)$ m $=300$ m

Required time $=\left(300\times\frac{9}{250}\right)$ sec $=\frac{54}{5}$ = 10.8 sec.