A train travelling with a speed of 60 kmph catches another train travelling in the same direction and then leaves it 120 m behind in 18 seconds. The speed of the second train is

Explanation:-

Let speed of the 2^nd train is S m/sec.
And,
60 kmph = ^(60*5)/₁₈ = ⁵⁰/₃ m/sec.
As trains are traveling in same distance, Then Relative distance,
(⁵⁰/₃) - S = ¹²⁰/₁₈;
Or, ^(50-3S)/₃ = ²⁰/₃;
Or, 50-3S = 20;
S = 10 m/sec.
Or, Speed of the 2^nd train = ^{10 * 18}/₅ = 36 kmph.