# Homework Help: 2-D Kinematics Riverboat problem, finding current strength?

1. Sep 18, 2010

### n92

2-D Kinematics Riverboat problem, finding current strength??

1. The problem statement, all variables and given/known data

A boat whose spead is 2.20 m/s in still water must cross a 260m river and arrive at a point 110m upstream from where it starts. The boat's pilot has a heading of 45 degrees upstream, what is the current speed?

2. Relevant equations

sine of the angle = Vbs/Vbw ?

Vbs - velocity of the boat relative to shore
Vbw - velocity of the water relative to shore
Vws - veloicty of the water relative to shore

3. The attempt at a solution

I'm very confused as how to tackle this problem, I started off finding the boat's velocity relative to the shore,

2.20cos45 = 1.56 m/s

Now that I have this I'd assume i could find the river's velocity using pathagorus, but the 45 degree angle and the fact that the boat is to travel in a line to a destination not directly in front of it has thrown me off.

Any pointers would me much appreciated, I'm more than likely missing a crucial step that I can't see..

Cheers.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution