1. a km / hr = (a * 5/18) m/s.
2. a m / s = (a * 18/5) km / hr.
3. Time taken by a train of length / meters to pass a pole or a standing man or a signal post is equal to the time taken by the train to cover 1 meters.
4. Time taken by a train of length / meters to pass a stationary object of length b meters is the time taken by the train to cover ( 1 + b) meters.
5. Suppose two trains or two bodies are moving in the same direction at u m /s and V m / s, where u > v, then their relatives speed = (u – v) m / s.
6. If two trains are moving in opposite directions at u m /s and V m / s, then their relative speed is = (u + v) m /s.
7. Assume two trains or two bodies are moving in opposite directions at u m / s and v m / s then their relatives and b meters are moving in opposite directions at u m /s and v m /s, then by the trains to cross each other =(a+b)/(u+v) sec.
8. If two trains of length a meters and b meters 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.
9. If two trains (or bodies) start at the same time from points A and B towards each other and after crossing they a and b sec in reaching B and A respectively, then (A’s speed) : (B’s speed) = (root of b: root of a).
https://gyangossip.com/quantitative-aptitude/mock-test/T4653
https://gyangossip.com/quantitative-aptitude/mock-test/T9211