Distance, Time & Speed
Speed Formula
Speed = Distance / Time
Unit Conversion
x km/hr = x (5/18) m/sec
x m/sec = x (18/5) km/hr
Tricks
If the ratio of speeds of A and B is a:b, then ratio of time taken by them is 1/a:1/b or b:a.
Suppose a train covers a certain distance at x kmph and an equal distance at y kmph. Then, the average speed during whole journey is 2xy / (x+y).