- Downstream/Upstream:In water, the direction along the stream is called downstream. And, the direction against the stream is called upstream.
- If the speed of a boat in still water is u km/hr and the speed of the stream is v km/hr, then:
Speed downstream = (u + v) km/hr.
Speed upstream = (u – v) km/hr.
- If the speed downstream is a km/hr and the speed upstream is b km/hr, then:
Speed in still water = 1 (a + b) km/hr. 2 Rate of stream = 1 (a – b) km/hr. 2