A man sitting on a train travelling at the rate of 50 km/hr observes that it…
2025
A man sitting on a train travelling at the rate of 50 km/hr observes that it takes 9 sec for goods train travelling in the opposite direction to pass him. If the goods train is 187.5m long. Find its speed.
Answer: C. 25 — Answer: 25 km/hr Steps: Convert the man's speed to m/s: 50 km/hr = 50 × 1000/3600 = 13.888... m/s. Relative speed (because trains move in opposite directions)…
- A.
35
- B.
75
- C.
25
- D.
12
Attempted by 14 students.
Show answer & explanation
Correct answer: C
Answer: 25 km/hr
Steps:
Convert the man's speed to m/s: 50 km/hr = 50 × 1000/3600 = 13.888... m/s.
Relative speed (because trains move in opposite directions) = length ÷ time = 187.5 m ÷ 9 s = 20.833... m/s, which equals 20.833... × 3.6 = 75 km/hr combined.
Goods train speed = combined speed − man's speed = 75 − 50 = 25 km/hr.
You can also check in m/s: goods speed = 20.833... − 13.888... = 6.94444 m/s, and 6.94444 × 3.6 = 25 km/hr.
Therefore the goods train's speed is 25 km/hr.