# Homework Help: Help me cross the river

1. Nov 10, 2004

### cubs1908

if jon rows a boat at 4m/s the river is moving at 6m/s and the river is 300m how long does it take to row across. I need the equation

2. Nov 10, 2004

### teclo

think about the reference frames. if you're standing aside, how fast is the river moving? how fast is the boat moving? which is moving faster, slower?

think about it from jon's point of view. if he does no work, how fast is he moving? how fast are you moving if he is observing you? he is doing work, so how is he moving in comparison to you and the river?

hopefully that helps

3. Nov 10, 2004

### Parth Dave

Rather then trying to find the equation, i suggest you try to understand whats happening in the problem. First of all, what is jons goal? What factors influence how this happens?

4. Nov 10, 2004

### UrbanXrisis

this question can change drastically with the direction of the rower and river. Are they in the same direction? Are the forces perpendicular?

t=d/v

Last edited: Nov 10, 2004
5. Nov 10, 2004

thanks alot