Trains - Important formulas
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km/hr to m/s conversion:
a km/hr = a x 5 m/s. 18 -
m/s to km/hr conversion:
a m/s = a x 18 km/hr. 5 -
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.
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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.
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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.
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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.
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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) sec. (u + v) -
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) sec. (u - v) -
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)
1. d
2. c
3. b
4. c
5. d
6. a
7. d
8. b
9. b
10. c
11. a
12. b
13. b
14. c
15. c
16. c
17. c
18. d
19. c
20. a
21. a
22. d
23. a
24. c
25. d
26. a
27. a
28. b
29. d
30. a
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