Formula Technique 16 (Boat or Swimmer in Stream)
Let speed of boat is V and speed of stream is U;
1- If swimmer goes down stream then his speed id U+V
2- If swimmer goes up stream his speed is V-U
If speed of a swimmer down stream is Ds and speed upstream is Us, then in still water (negligible or slow flow of water);
1- Speed of swimmer = 1/2(Ds+Us) {i-e his average speed)
2- Speed (relative or w.r.t the swimmer) of stream = 1/2 (Ds-Us) (average of vector sum)
