# Parallelagram of forces

#### manich43

Can someone show me how to calculate the resultant forces shown as RF N and R F 1on the attachment please, in simple terms.

2.I need to work out the following..."Three forces applying to one point,find the resultant force" (magnitude and direction to horizontal line) R F1 and R F N

3.Any help greatly appreciated.

Mark

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#### LowlyPion

Homework Helper
Welcome to PF.

The approach that works best for me is the component approach.

What you have is a vector addition in x,y

So try taking each Force vector as

Fv1 = fx1 i + fy1 j
Fv2 = fx2 i + fy2 j
Fv3 = fx3 i + fy3 j

Then just add the i's and the j's and you have your resultant

F = (fx1+fx2+fx3) i + (fy1+fy2+fy3) j

#### manich43

Hi,
Dont really follow that.This is the first time i have seen a parallelogram of forces.Can you explain how I would find the resultant force in N for RF 1 and RF N on the diagram.

Many Thanks....Mark

#### tiny-tim

Homework Helper
Welcome to PF!

This is the first time i have seen a parallelogram of forces.Can you explain how I would find the resultant force in N for RF 1 and RF N on the diagram.
Hi Mark! Welcome to PF!

Forces are vectors, so they obey the law of vector addition …

that means that to add two vectors, you slide one so that it starts where the other one ends

in other words, you make a vector triangle …

but it comes out the same if you start both of them from the same point, and make a parallelogram (as in your diagram) …

to convince yourself that they're the same, just try sliding one of the sides of the parallelogram along to the opposite side

#### manich43

Thanks to all who replied,problem solved!

Mark

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