- #1
thepopasmurf
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I'm studying for an exam and this is one of the sample questions which I cannot figure out.
Two ships A and B move with constants speeds 48 km/h and 60 km/h respectively. At a certain instant ship B is 30 km west of A and is traveling due south. Find:
i) The direction ship A should steer in order to get a close as possible to ship B.
Vab = Va - Vb
Well, Vb = 0i - 60j
Va = -48cosxi - 48sinxj
and therefore
Vab = -48cosxi + (60 - 48sinx)j
I have drawn diagrams to help but I can't figure out the right angle. I tried differentiation to find the lowest possible value for j (they are already horizontally across from each other) but I got 1 for an answer which I know is not correct. Any advice.
Homework Statement
Two ships A and B move with constants speeds 48 km/h and 60 km/h respectively. At a certain instant ship B is 30 km west of A and is traveling due south. Find:
i) The direction ship A should steer in order to get a close as possible to ship B.
Homework Equations
Vab = Va - Vb
The Attempt at a Solution
Well, Vb = 0i - 60j
Va = -48cosxi - 48sinxj
and therefore
Vab = -48cosxi + (60 - 48sinx)j
I have drawn diagrams to help but I can't figure out the right angle. I tried differentiation to find the lowest possible value for j (they are already horizontally across from each other) but I got 1 for an answer which I know is not correct. Any advice.