Question

A train from Mumbai to Pune and another from Pune to Mumbai start at the same time, cross one another en route and reach their destinations in 4 hours and 1 hour, respectively, after crossing. If the first train was travelling at 24 kmph, at what speed was the second train travelling?

Accepted Answer

B. The standard relationship for speeds of two bodies after crossing each other is: $$\frac{S_1}{S_2} = \sqrt{\frac{T_2}{T_1}}$$ Given $S_1 = 24$, $T_1 = 4$ hours, $T_2 = 1$ hour. $$\frac{24}{S_2} = \sqrt{\frac{1}{4}} = \frac{1}{2} \implies S_2 = 48 	ext{ kmph}.$$

Speed of Trains after Crossing

Explanation

Practise this under exam conditions