Problems on Trains
1. km/hr to m/s conversion:
a km/hr =a * 5/18 m/s.
2. m/s to km/hr conversion:
a m/s =a * 18/5 km/hr.
3. Formulas for finding Speed, Time and Distance
4. Time taken by a train of length l metres to pass a pole or standing man or a signal post is equal to the time taken by the train to cover l metres.
5. Time taken by a train of length l metres to pass a stationery object of length b metres is the time taken by the train to cover (l + b) metres.
6. Suppose two trains or two objects bodies are moving in the same direction at u m/s and v m/s, where u > v, then their relative speed is = (u – v) m/s.
7. Suppose two trains or two objects bodies are moving in opposite directions at u m/s and v m/s, then their relative speed is = (u + v) m/s.
8. If two trains of length a metres and b metres are moving in opposite directions at u m/s and v m/s, then:
The time taken by the trains to cross each other =(a + b)/(u + v)sec.
9. If two trains of length a metres and b metres are moving in the same direction at u m/s and v m/s,
then:The time taken by the faster train to cross the slower train =(a + b)/(u – v)sec.
10. If two trains (or bodies) start at the same time from points A and B towards each other and after crossing they take a and b sec in reaching B and A respectively, then: (A’s speed) : (B’s speed) = (b : a)
- A train running at the speed of 60 km/hr crosses a pole in 9 seconds. What is the length of the train?
A. 120 metres
B. 180 metres
C. 324 metres
D. 150 metres
- A train 125 m long passes a man, running at 5 km/hr in the same direction in which the train is going, in 10 seconds. The speed of the train is:
A. 45 km/hr
B. 50 km/hr
C. 54 km/hr
D. 55 km/hr
- The length of the bridge, which a train 130 metres long and travelling at 45 km/hr can cross in 30 seconds, is:
A. 200 m
B. 225 m
C. 245 m
D. 250 m
- Two trains running in opposite directions cross a man standing on the platform in 27 seconds and 17 seconds respectively and they cross each other in 23 seconds. The ratio of their speeds is:
A. 1 : 3
B. 3 : 2
C. 3 : 4
D. None of these
- A train passes a station platform in 36 seconds and a man standing on the platform in 20 seconds. If the speed of the train is 54 km/hr, what is the length of the platform?
A. 120 m
B. 240 m
C. 300 m
D. None of these