A swimmer's speed in the direction of flow of a river is 12kmh^(-1). Against the direction of flow of the river the swimmer's speed is 6kmh^(-1). Calculate the swimmer's speed in still water and the velocity of the river flow.

A swimmer's speed in the direction of flow of a river is 12kmh^(-1). A

1.	A swimmer's speed in the direction of flow of a river is 12kmh^(-1). Against the direction of flow of the river the swimmer's speed is 6kmh^(-1). Calculate the swimmer's speed in still water and the velocity of the river flow.
Answer» SOLUTION :Let `v_(s)andv_(r)` represent the VELOCITIES of the swimmer and river respectively with respect to ground. `v_(s)+v_(r)=12""…..(1)` and `v_(s)-v_(r)=6""…..(2)` Adding the both EQUATIONS(1) and (2) `2v_(s)=12+6=18kmh^(-1)orv_(s)=9kmh^(-1)`. From EQUATION (1), `9+v_(r)=12orv_(r)=3kmh^(-1)` When the river flow and swimmer move in the same direction, the net velocity of swimmer is 12 kmph.