Question

A 220 metre long train is running at a speed of 54 kilometre per hour. In what time will it pass a man who is moving in the opposite direction of the train at speed of 12 kilometre per hour?

• A. 6 sec
• B. 10 sec
• C. 8 sec
• D. 12 sec

Answer 1

Answer:

D. 12 sec

Solution:

Concept:

When two bodies run in the opposite direction, then their relative velocities get added.

1 km/hr = 5/18 m/s.

1 m/s = 18/5 km/hr.

Calculation:

Length of train = 220 m, Speed of train = 54 km/hr ⇒ 15 m/s and Speed of man = 12 km/hr ⇒ 10/3 m/s [ 1 km/hr = 5/18 m/s]

$Times=\frac{Distance}{Speed}$

$\frac{220}{\frac{10}{3}\;+\;15}$ ----(Speed gets added due to different direction)

$\frac{220\times{3}}{55}$

$=12sec$