3).
Time taken by a train of length l meters to pass a pole or a standing man or a signal post is equal to the time taken by the train to cover l meters.
4).
Time taken by a train of length l metres to pass a stationary object of length b metres is the time taken by the train to cover (l + b) metres.
5).
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.
6).
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 bsec in reaching B and A respectively, then