mass of e is 100 kg(adsbygoogle = window.adsbygoogle || []).push({});

mass of bar is 20 kg and acts at midpoint

sume of moments about point a due to weight of bar and forces on b by bc, bd, and be, are 0, determine tensions in bc and bd

so i continued like this.

The moment about point A from all those forces is 0.

0 = (Raf x Wab) + (Rab x Wbe) -(Rab x Tbc) - (Rab x Tbd)

I can figure out the first two terms of this eq, but i have to find magnitude of the vectors of Tbc and Tbd. But i only have this equation and these two equations:

Tbc= |Tbc|*Ebc where Ebc is a unit vector in BC direction

Tbd= |Tbd|*Ebd where Ebd is a unit vector in the BD direction

Did i set this up incorrectly or how do i proceed?

a picture has been included.

Thanks for your help

Pt A is at the origin

Pt D is (0,5,5)

Pt C is (0,4,-3)

Pt B is (4,3,1)

Pt E is where the 100 kg weight is

AB is the bar where 20 kg acts down the midpoint

any help is APPRECIATED!

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# Homework Help: Moments about a point

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