In force-couple system equivalence, We can show that two systems are equivalent if the resultant force in both are equal and that it has the same line of action.(adsbygoogle = window.adsbygoogle || []).push({});

So Rx1 = Rx2, Ry1= Ry2, Ma1 = Ma2

Now my book says we can use another form of equation: We can choose 3 point and find the moment about them and use it to find the equivalent force, as long as a, b and c are not on the same line

I fail to see why should this work.

Ma = x Ry -y Rx

Mb = x Ry - y Rx

Mc = x Ry - y Rx

THe x and ys in each equation is different, How do you solve such a system to find Ry and Rx and the line of action? You can also use 2 moments and 1 resultant force equation in x or y direction

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# I Force-couple system equivalence: 3 moment equations

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