(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

The problem is actually for a car but I'm going to simplify it so it''s easier to type on here. Basically there's a point (let's call it point A) located at (-1,-.5)m. An upward force A acts at point A with 7000N and a horizon force F acts on point A but points left so it's negative. The resultant force due to A&F makes an angle 15 deg w/ respect to the vertical. Determine the equivalent force couple system at the origin. Basically I find the moment.

2. Relevant equations

i choose to do the cross product M=rxR, where R=resultant force

3. The attempt at a solution

1. I found force F by doing tan(15)=F/7000 which gave me F=1875.6N <<<magnitude or -1875.6N

2. so R=7000i-1875.6j N

3. Then I found r by doing point A-origin which would be <-.5,-1>-<0,0> which got me -1i-.5j m

Then I took the cross product rxR and got -7938 N.

The answer in the book was 7938 N. I don't understand why they had a positive answer, it's obvious that the answer should be negative because the moment is acting in a clockwise direction.

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# Homework Help: Find the force-couple system check my answer please

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