A river flows due south with a speed of 2.0 m/s. A man steers a motorboat across the river. The river is 800 m wide.
In which direction should the motorboat head in order to reach a point on the opposite bank directly east from the starting point? (The boats speed relative to the water is 4.2 m/s.)
What is the velocity of the boat relative to the earth?
How much time is required to cross the river?