- #1
kudoushinichi88
- 129
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Homework Statement
The water in a river flows uniformly at a constant speed of 2.50m/s between two parallel banks 80.0m apart. You are to deliver a package directly across the river, but you can only swim at 1.5m/s.
If you choose to minimize the distance downstream that the water carries you, in what direction should you head?
Homework Equations
x=x_o+v_xt
The Attempt at a Solution
Let's say the river is flowing towards the east and taking that as the x-axis, you must swim at some angle, x from the x-axis in the opposite direction of the flow of the river.
To have a minimum distance downstream, I figure that we must have zero displacement on the x-axis and a displacement of 80m on the y-axis.
So I came up with this right angled vector triangle with hypotenus 1.5(cos x)t and sides 80 and 2.5t. Using the Pythagoras theorem, I came up with
t = sqrt(6400/(2.25Cos^2 (x)-6.25))
but now I'm stuck! cos I think I'm conceptually flawed right from the start.
Please help! this question is driving me crazy!