A boat crosses a river and arrives at a point on the opposite bank directly across from its starting position. The boat travels at 4 m/s and the current is 2m/s. If the river is 600 m wide in what direction must the boat steer and how long will it take to cross?

1 answer

want to go East
current 2 south
C = true compass heading
Vnorth = 0 = 4 cos C - 2
cos C = 1/2
C = 60 degrees East of North
Veast = 4 sin 60 = 4 (sqrt 3)/2 = 2 sqrt 3
600 = t * 2 sqrt 3
t = 300/sqrt 3