Q149
ArithmeticSpeed, Time & Distance
Running at a speed of 60 km per hour, a train passed through a 1.5 km long tunnel in 2 minutes. What is the length of the train?
- a.250 m
- b.500 m
- c.1000 m
- d.1500 m
Answer: (B) 500 m
60 km/h is 1 km per minute, so in 2 minutes the train travels 2 km. To pass completely through a tunnel a train must cover the length of the tunnel plus its own length, so its length is $2 - 1.5 = 0.5$ km $= 500$ m. The same rule applies to bridges and platforms: distance covered equals the length of the object plus the length of the train, whereas for passing a pole or a standing man it is the train's length alone. Useful conversion: 1 km/h $= \frac{5}{18}$ m/s, so 60 km/h $= 16\frac{2}{3}$ m/s.