Question

A 210 m long train crosses a man running at 9 kmph in opposite direction in 6 seconds.Find the speed of the train

Answer 1

Speed of man = 9 kmph = (9 *5)/18 = 5/2 m/sec.

Let speed of the train = X m/sec

Relative speed = X + 5/2 m/sec. [Both are moving opposite direction.]

Length of the train = 210 m

Time taken to cross = 6 sec.

Now,

ST = D

(X + 5/2 ) * 6 = 210

X + 2.5 = 35

X = 35 - 2.5 = 32.5 m/sec = (32.5 *18) /5 = 117 Kmph.