Fri September 28, 2012 By:

A swimmer can swim in still water at a rate of 4kmph. If he swims in a river flowing at 3kmph and keeps his direction with respect to water perpendicular to the current, find his velocity and direction with respect to the ground?

Expert Reply
Sun September 30, 2012
velocity of swimmer wrt ground: v = 4 kmph
velocity of river wrt ground: u = 3kmph
angle between his velocity and river: 90 degrees
thus relative velocity of that swimmer in water wrt ground: (u2 + v2)1/2= 5 kmph
and angle  is given as: tan-1(3/4)
Ask the Expert