A man riding a bicycle at 90 km/hr crosses a bridge in 37 minutes. Find the…

Concept

For motion at a constant speed, distance equals speed multiplied by time: Distance = Speed × Time.

All quantities must use compatible units before the formula is applied.

Application

1. Treat the rider and bicycle as a point object, so the distance travelled while crossing is the bridge length.

2. The speed is 90 km/hr and the time is 37 minutes.

3. Convert the time to hours: 37 minutes = 37/60 hour.

4. Apply the relation: Distance = 90 × (37/60) km.

5. Simplify: Distance = (90/60) × 37 = 1.5 × 37 = 55.5 km.

Cross-check

At 90 km/hr, the distance covered in one minute is 90/60 = 1.5 km. In 37 minutes, the distance is 1.5 × 37 = 55.5 km, which agrees with the main calculation.

Therefore, the bridge is 55.5 km long.