Question

A railway track runs parallel to a road until a turn brings the road to railway crossing. A cyclist rides along the road every day at a constant speed $20km/hr$. He normally meets a train that travels in same direction at the crossing. One day he was late by $25$ minutes and met the train $10km$ before the railway crossing. Find the speed of the train.

• A. 9 ,km/hr
• B. 90 km/hr
• C. 120 km/hr
• D. 40 km/hr

Answer 1

Answer: (C)

$t_{\text{cycle}}=\frac{10km}{20km{h}^{-1}}$

$=\frac{1}{2}h=30\min$

$\Delta t=5\min =\frac{5}{60}hr$



Train running as per schedule.

So $V_{\text{train}}=\frac{10}{(5/60)}$

$=\frac{10\times 60}{5}$

$=120km{h}^{-1}$