RRB Group-D Model Paper 15 with answers for online practice

Question : 93 of 100

Marks: +1, -0

A train, 200 m long, passes a pole in 20 seconds and crosses another train of the same length travelling in the opposite directions in 10 seconds. The speed of the second train is

10 m/s
12 m/s
30 m/s
16 m/s

Validate

Solution:

When a train passes a pole it essentially travels a distance equal to its own length.
Given, train, 200 m long, passes a pole in 20 seconds.
Speed of this train = 200/20 = 10 m/s
Also, when a train crosses another train, it travels a distance equal to the sum of lengths of both the trains, at relative speed.
Given, it crosses another train of the same length travelling in the opposite directions in 10 seconds.
Let the speed of

2^{nd}

train be a.
Relative speed = (10 + a) m/s
Total distance = 200 + 200 = 400 m
∴ 10 + a = 400/10
⇒ a = 30 m/s

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