posted by Ashley
A swimmer heads directly across a river, swimming at 1.10 m/s relative to the water. She arrives at a point 52.0 m downstream from the point directly across the river, 72.0 m wide. What is the speed of the river current? What is the swimmer's speed relative to the shore? In what direction (as an angle relative to a direct line across the river) should the swimmer aim instead, so that she arrives at the point directly opposite her starting point?
at 1.1m/s, she takes 72/1.1 = 65.45 seconds to cross
In that time she travels downstream 52m, so the current is 52m/65.45s = .794m/s
with that, you should be able to get the angle needed.