Important Maths Formulas of Distance, Time and Speed
Speed 

Distance 
Distance = Speed × Time 
Time 

Average Speed 

 To convert a speed in m/s to km/h, multiply by 18/5.

 To convert a speed in km/h to m/s, multiply by 5/18.

 Time taken by a train x metres long to pass a stationary object
= Time Taken by it to cover x metres 
 Time taken by a train x metres long to pass a platform or tunnel y metres long
= Time taken by it cover (x + y) metres. 
 If two objects are moving in opposite directions towards each other with speeds x km/h and y km/h respectively, then their relative speed is ( x + y) km/h.

 If two objects are moving in the same direction with speeds x km/h and y km/h respectively, such that x > y, then their relative speed is (x – y) km/h.

 If the speed of a boat in still water is x km/h and the speed of the stream is y km/h, then:
Speed downstream = (x + y) km/h
Speed upstream = (x  y) km/h 