Quantitative Aptitude - Problem On Trains - Formula & Concept Tutorial

1. To convert km/hr to m/sec

x km/hr = ( x * 5/18) m/sec

2. To convert m/sec to km/hr

x m/sec = (x * 18/5) km/hr

3. Time taken by a train of length l metres to pass a pole or a standing man or a signal post is equal to the time taken by the train to cover l metres.
4. Time taken by a train of length l metres to pass a stationary object b  metres is the time taken by the train to cover ( l + b ) metres.
5. Suppose two trains or two bodies are moving in the same direction at u m/s and v m/s , then their relative speed is ( u - v ) m/s
6. Suppose two trains or two bodies are moving in the opposite direction at u m/s and v m/s , then their relative speed is ( u + v ) m/s
7. If two trains of length a metres and b metres are moving in opposite direction at u m/s and v m/s , the time taken by train to cross each other is  sec.
8. 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 is  sec.
9. If two trains 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 =