# Crossing a River

1. Jan 25, 2005

### sundrops

A swimmier heads across a river, swimming at 1.20m/s relative to still water. It arrives at a point 67.0 m downstream from the oint directly across the river, which is 100.m wide. What is the speed of the river current?

Here's what I did:

tan^-1(67/100)
theta = 33.82 degrees

Vx = Vxocos(33.82)
Vx = 1.20m/s * cos(33.82)
Vx = 0.997m/s

and since the current is moving in the opposite direction it would be -0.997m/s.

2. Jan 25, 2005

### sundrops

it's wrong.

So obviously my method of getting the answer was flawed aswell. Is there another way to solve this problem?

3. Jan 25, 2005

### marrsc

Determine the time it takes to cross the river. In this period the swimmer drifts 67 m. Solve for the current speed.

4. Jan 25, 2005

### learningphysics

1.20 m/s is the speed of the swimmer in still water. Not his total speed. His velocity is 1.20 m/s in the x-direction (direction across river), and v in the y-direction(along the river), where v is the river speed. How long does it take him to cross the river?