Statics - beam forces and moments

[almoga]

Summary:: I did the first section but I am having a hard time with the second. would like to find the moment in the next section (from b to h)

 

[willem2]

I don't think your momentum is right. The momentum in the top beam ranges from 0 at the corner to Pb at the wall, so pb+px can't be right, however you define x. (I don't see it on the drawing)
When analyzing a beam in wall/floor problem, it's usually easiest to start at the end of the beam. The section from h to the end is very simple, so you can also analyze the section from the cut in the top beam to the end at once. There really shouldn't be a problem if you set the total force and the momentum at any point at 0.

 

[almoga]

you were right about the b section. I corrected it. I ended up with a constant momentum of zero at the h section. does this make sense to you?

 

[willem2]

I think you can replace the vertical beam with a rope. There's only vertical forces, so how could there be a momentum?

 

[Dr.D]

I don't think your momentum is right. The momentum in the top beam ranges from 0 at the corner to Pb at the wall

you were right about the b section. I corrected it. I ended up with a constant momentum of zero at the h section

If this is truly a statics problem, there is no momentum involved at all. There seems to be confusion between a "moment" and "momentum." They are quite different matters.

 

[Chestermiller]

I think you can replace the vertical beam with a rope. There's only vertical forces, so how could there be a momentum?

You need to balance forces and also moments.

 

[Chestermiller]

The moment in the horizontal section is P(b-x). Basically, this is the same thing as a cantilever beam without the vertical section.