Posted by yonela on .
a river flows due south with a speed of 2.0m/s. a man steers a motorboat across the river;his velosity is 4.2m/s due east.the river is 800m wide.
(A) what is his velocity(magnitude and direction)relative to the earth?
(B)how much time is required to cross the river?

physics111 
bobpursley,
b. time to go across: distanceEast/VelocityEast
a. he is heading upstream:
direction=arctan2/4.2
magnitude: speed=sqrt(4.2^2+2^2)