-->

Motion In A Plane

Question
CBSEENPH11018640

Two trains 120 m and 80 m in length are running in opposite direction with velocities 42 km/hr and 30 km/hr. In what time they will complete cross each other? 

Solution

Relative velocity of one train w.r.t second, 
= 42 - (-30)
= 72 km /hr
= 20 m/s 
Total distance to be travelled = 120 + 80 = 200 m
Time taken  = 200/20 = 10 sec