# Equivalent force systems (statics)

1. Feb 3, 2010

### jegues

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

2. Relevant equations
$$\sum F_{x} = 0$$

$$\sum F_{y} = 0$$

3. The attempt at a solution

I'm confused as to how to check which systems are equivalent.

Do I just have to simply reduce all the systems to one force?

I tried comparing systems (a) and (b) and they don't seem to be the same.

If I take moments about the bottom left corner,

$$M_{a} = 63N.m$$
$$M_{b} = 35N.m$$

I'm confused as to which route I should take to solve the problem. Any ideas?

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Last edited: Feb 3, 2010
2. Feb 3, 2010

### PhanthomJay

No figure attached.

3. Feb 3, 2010

### jegues

Sorry about that, it should be in the OP now.

4. Feb 3, 2010

### PhanthomJay

The force systems are equivalent if the resultant force and moments about a point, of each system, are the same. You are correct that 'a' and 'b' are not equivalent. What about 'a' and 'c'???

5. Feb 4, 2010

### jegues

That's all I needed!

Thank you!