a few questions

[kathryn]

I realize that these are really easy questions, but Im just starting a correspondence course and I need to finish the first half of my physics course in less than a month to graduate. Thanks for any help!!

1. A straight river with parallel banks flows at 4 km/h. A boat moves directly downstream relative to the water at 11 km/h. The velocity of the boat relative to the river bank is...____________

2. If the boat moves directly upstream relative to the water of the river of #1, at 9 km/h, its velocity to the river bank is now..._________

Thanks for any help at all...

[whozum]

Its moving 11km/h faster than the water is, right? So how fast is that on the stream?
If your on the freeway going 50mph relative to the ground and someone passes you going 10mph faster than you are, how fast are they going relative to the ground?

2. Its the same thing except opposite direction, try to set up a "forward direction", then if your good with vectors your good to go.