Time and Distance

TIPS AND FORMULAS ON TIME AND DISTANCE:

1. Speed =  Distance/Time

2. Time =  Distance /Speed

3. Distance = Speed x Time

4. km/hr to m/s conversion:
1 kmph =   5/18 m/s
5. m/s to km/hr conversion:

 1 m/s =   18/5 m/s

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/(x + y) km/h

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)/(u - v) sec.

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)/(u + v) sec.

14.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) = Öb : Öa