(i)two trains running in opposite directions at 36 km/hr and 45 km/hr cross each other in 20 s.if one train is 200 m long,the length of another train is
(a) 200 m(b)250 m (c)300 m (d)none
(ii)a train 220 m long is running with a speed of 60 km/hr.in what time will it cross a man who is running at 6 km/hr in direction opposite to that in which the train is going.
(a)12 sec (b)12 min (c)12 hours (d) none
please tell the questions in detail.tell me fast

1

Answers

2015-09-11T02:29:28+05:30

This Is a Certified Answer

×
Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
1)
Relative velocities of the two trains = 36 + 45 = 81 kmph
The time duration for the cross over = 20 sec.
the total distance travelled in 20sec at relative velocity = 81 kmph * 5/18 * 20 sec
       = 450 m

Length of the second train = 450 m - 200 m = 250 meters.
============
b)
relative velocity of the train and person = 60 kmph + 6 kmph = 66 kmph
   = 5/18 * 66 = 55/3 m/s
length of distance to cross = length of train = 220 m
time duration to cross = 220 / (55/3) = 12 sec.

1 5 1