How far downstream has the boat moved?

[asloudascanbe]

[SOLVED] How far downstream has the boat moved?

I can't figure out the last part of this question. It's probably very simple and I'm just over looking it. The answers in part A are right. I just don't know how to get part B.

A river flows due east at 1.80 m/s. A boat crosses the river from the south shore to the north shore by maintaining a constant velocity of 9.0 m/s due north relative to the water.

(a) What is the velocity of the boat relative to shore?
9.178 m/s
78.69° (north of east)


(b) If the river is 400 m wide, how far downstream has the boat moved by the time it reaches the north shore?
m

 

[arildno]

1. Find out the time the boat takes to traverse the 400 meters in the northern direction, at speed 9 m/s

2. Then find out the boat's (eastern) dowstream displacement in the same time .

 

[asloudascanbe]

So to fine the time it takes the boat to go 400 meters at a speed of 9 m/s. I divided 400/9.0 and got 44.4444s.

Then I thought to find the downstream displacement given that time you would just divide the 44.444s/(1.8m/s)? But that's wrong and I don't know what else to do?

 

[arildno]

What is distance?

Velocity MULTIPLIED WITH time!

 

[asloudascanbe]

SOLVED thanks...sorry for some reason I thought you divided it.