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Force projection onto body's axis

by Bismuth
Tags: axis, body, force, projection
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Sep20-10, 12:09 AM
P: 6
Hey PhysicsForums. Long time reader looking for some assistance

1. The problem statement, all variables and given/known data

2. The attempt at a solution

I'm pretty sure the idea is to find the unit position vector to point A, and the force vector F.

I found the unit position vector to be u = (-4/6)i +(4/6)j + (2/6)k, and the force to be F = (560cos60sin30)i + (560cos60cos30)j + (560sin60)k

Dotting them together gives me 230 lb, but Mastering Engineering doesn't agree with me. Can anyone point out where I went awry?

Thanks for reading!
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Sep20-10, 04:28 AM
Sci Advisor
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PF Gold
P: 11,768
The x-component of F should be negative. The rest looks fine to me.
Sep20-10, 08:24 AM
P: 6
Simple mistakes are embarassing :(

Thank you for your careful eyes!

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