A river d km wide is flowing at the rate A swimmer which can swim with velocity relative to water wants to cross the river straight across. Find how long will he take to cross the river?
Let the three forces acting at point O be in equilibrium.
Here, velocity of man is, v = 5 km/hr
Velocity of river is, u = 3 km/hr along QP
Swimmer A:
Velocity of swimmer A w.r.t. bank while going from P to Q = v - u
Velocity of swimmer A w.r.t. bank while coming back from Q to P = v + u
Time taken by swimmer A to make the round trip is,
or
Swimmer B:
To cross the river straight across man will dive at angle ***** (shown in figure) given by
Therefore time taken by man B to make the round trip is,
The difference of the time taken by two swimmers is
A stream of width d is flowing with velocity v. A person who can swim with speed V relative to water wishes to row straight across it. In what direction should he strike out and how long would it take him to cross the stream?