Question

The length of the train, which is travelling with a speed of 45 km/h, and can cross a 100 m long bridge in 30 sec, is:

• A. 225 m
• B. 245 m
• C. 275 m
• D. 200 m

Hint:

When a train crosses a bridge, the total distance covered is the sum of the length of the train and the length of the bridge.

Answer 1

The Correct Option is C

Step 1: Convert speed to m/s. \[ \text{Speed} = 45 \, \text{km/h} = 45 \times \frac{1000}{3600} \, \text{m/s} = \frac{45 \times 1000}{3600} = 12.5 \, \text{m/s}. \] Step 2: Total distance covered by the train in 30 seconds. \[ \text{Distance covered} = \text{Speed} \times \text{Time} = 12.5 \, \text{m/s} \times 30 \, \text{sec} = 375 \, \text{m}. \] Step 3: Length of the train. The total distance covered is the sum of the length of the train and the length of the bridge (100 meters): \[ \text{Length of the train} = \text{Total distance covered} - \text{Length of the bridge} = 375 \, \text{m} - 100 \, \text{m} = 275 \, \text{m}. \]