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__Formulas of Problems on Trains - Aptitude Questions and Answers.__

**TIPS AND FORMULAS FOR SOLVING QUESTIONS RELATED TO TRAINS:**

1. Speed = __ Distance __

Time

2. Time = __ Distance __

Speed

3. Distance = Speed x Time

4. km/hr to m/s conversion:

1 kmph = __ 5 __ m/s

18

5. m/s to km/hr conversion:

1 m/s = __ 18 __ m/s

5

6. If the ratio of speeds of train A and B is a : b, then the ratio of time taken by them to cover the same distance = b : a.

7. If a man covers a certain distance at x km/hr and an equal distance at y km/hr. Then,

the average speed during the whole journey is

__ 2xy __ km/h

x + y

8. The time taken by a train in passing a pole or standing man is the same as the time taken by the train to cover a distance equal to its own length.

9. The time taken by a train of length 'L' metres in passing a stationary object of length 'B' metres is equal to the time taken by the train to cover a distance equal to (L + B) m.

10. If two trains are moving in the same directions at u m/s and v m/s, where u > v, then their relative speed will be equal to the difference of their speeds i.e. (u - v) m/s.

11. If two trains are moving in the opposite directions at u m/s and v m/s, then their relative speed will be equal to the sum of their speeds i.e. (u + v) m/s.

12.If two trains of length 'a' metres and 'b' metres are moving in the same directions at u m/s and v m/s respectively,
then:

The time taken by the faster train to cross the slower train is

__(a + b)__ sec.

(u - v)

13.If two trains of length 'a' metres and 'b' metres are moving in the opposite directions at u m/s and v m/s respectively,
then:

The time taken by the faster train to cross the slower train is

__(a + b)__ sec.

(u + v)

10.If two trains start at the same time from points A and B towards each other and after crossing they take 'a' and 'b' hour in reaching B and A respectively, then:

(A's speed) : (B's speed) = √ b : √ a