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!

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Moments about a point

**Physics Forums | Science Articles, Homework Help, Discussion**