# Homework Help: Bending Moment in two directions

1. Sep 14, 2011

### shauntur

Not Really a homework question but it will help with how i go about the homework.

So i have a beam coming out of the wall and it has force acting on it like this:
Woops, that 20 on the side view should be a 10 :P

What i want to find is the total moment at the mid point. I know how to find the moment in each direction but im not sure if im aloud to add them together or use pythag??
heres my solution for each direction:

Can i just go sqrt(10^2+10^2) to give me 10?
Thanks
Shaun

2. Sep 14, 2011

### PhanthomJay

Hi Shaun, welcome to PF!
Moments are vectors and as such, have both magnitude and direction. So aside from the fact that sqrt(10^2+10^2) = 10(sq root 2) , its magnitude, there is a direction associated with the moment also (what is it?). Sometimes it is best to leave the moment in its component form....M = Mx + My.

3. Sep 14, 2011

### shauntur

thanks heaps mate, probably shouldnt be doing engineering if i cant use pythag properly :tongue:
really appreciate ur help

4. Sep 14, 2011

### pongo38

In your M diagrams, the horizontal one shows an assumed hinge at the wall, whereas the vertical one assumes moment-fixity. This may not affect your answer to the moment at midpoint of the beam.