A 375 m long train passes a man travelling in the opposite direction at a speed of 10.2 km/h in 15 seconds. Find the speed of the train (in km/h).

Given:

• Train length = 375 m
• Time = 15 sec
• Man’s speed = 10.2 km/h (opposite direction)

Step 1: Relative Speed (m/s)

Opposite direction ⇒ speeds add होंगी

Man’s speed in m/s:
$10.2 \times \frac{5}{18} = \frac{51}{18} = 2.83\ \text{m/s}$

Relative speed:
$\frac{375}{15} = 25\ \text{m/s}$

 Step 2: Train speed (m/s)

Train speed = Relative speed − Man speed

$= 25 - 2.83 = 22.17\ \text{m/s}$

 Step 3: km/h में convert

$22.17 \times \frac{18}{5} \approx 79.8\ \text{km/h}$

Final Answer:

👉 79.6 km/h