# engineering away from circuits (CWM=ACWM)

Discussion in 'Homework Help' started by lomax1, Mar 19, 2014.

1. ### lomax1 Thread Starter New Member

Feb 6, 2014
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0
Hi all,

A uniform horizontal beam: RA to RB is 8m

CWM = (2x20)+(5x5)+(7x30)+(9×15) = ACWM 40 + 25 + 210 +135

Not taking the 1st term (1x15) = (6×20)+(3x5)+(1×30) .I am confused with how you jump to 6x20 (and so on) my logic is to ad the surplus 1 on the end to the first moment of 2 at RA add that to the second moment of 3 to get 6 and x that by 20?
Without being able to draw s diagram its hard to describe. I believe im on the right track...

2. ### Papabravo Expert

Feb 24, 2006
11,163
2,186
I have no clue what track you are on. The diagram isn't just a thing -- it is the ONLY thing. Words fail me here to describe my opinion.

3. ### MrChips Moderator

Oct 2, 2009
14,519
4,282
I doubt that anyone here can help you. We have no idea what you are referring to.
Perhaps you fail to provide us with some vital information.
A diagram would also help.

4. ### lomax1 Thread Starter New Member

Feb 6, 2014
27
0
Thought it was a long shof as it structural. I couldnt be anymore to the point with my description ( I am sure someone will tell me otherwise)

No worries

5. ### MrChips Moderator

Oct 2, 2009
14,519
4,282
What is the meaning or origin of (2x20), for example?

It could mean 2t x 20m, 2mm x 20kg, 2A x 20V, etc.

6. ### lomax1 Thread Starter New Member

Feb 6, 2014
27
0
There are no units as they are 'moments' ! Its ok ......man

7. ### shteii01 AAC Fanatic!

Feb 19, 2010
3,975
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It looks like we are dealing with Statics problem. EE students are usually required to take one or two "mechanical" courses. I think my school now has a course where they rolled statics and dynamics material into one course. I got lucky in that when I went through the program we had a choice so I took just statics.

8. ### lomax1 Thread Starter New Member

Feb 6, 2014
27
0
Yes, equilibriam in beams and pillars etc. (Clockwise movements) CWM have to equal (Anti clockwise movements) ACWM. Do you know anything about this? Im just confused in the huge jump in numbers on the reverse?

9. ### shteii01 AAC Fanatic!

Feb 19, 2010
3,975
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Need much better description of the problem. Which usually done with a picture.

It has been a few years since I took that statics course I mentioned. If I remember basic setup, then the type of the "connections" are important. A beam pinned in place has one set of forces acting on that end. A beam that is not pinned and, for example supported under it, is then allowed to move in one dimension and will have a different set of forces acting on it.

Without a good illustration of the problem setup, I am not even going to bother trying to figure it out. Even if there was a good illustration, I would need to dig up my Statics textbook and my notes to make sure I am doing things right.

10. ### lomax1 Thread Starter New Member

Feb 6, 2014
27
0
This is the problem im hitting again and again with this forum (lol) I have no picture just text from a credible ( which I do question) university in the UK. I am armed soley with a text book which does exactly what it says on the tin......'text'. Its very frustrating. No worries thanks anyway

11. ### Papabravo Expert

Feb 24, 2006
11,163
2,186
What a steaming pile!!
Draw a picture -- find a scanner. How hard could it be? You're going to have a great deal of trouble in industry if you can't send a picture.

Last edited: Mar 19, 2014
12. ### shteii01 AAC Fanatic!

Feb 19, 2010
3,975
617
Your presentation of the material is very poor.

If you clearly understand the problem and just having difficulty solving it. Why not draw a picture for us. Label the forces, label the moments. You provided a couple of equations, but we don't know if we are looking at scalar product or at vector cross product.

Frankly I am not interested in playing Game of 101 Questions.

My Statics textbook, from a few years ago.

• ###### statics.jpg
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Last edited: Mar 19, 2014
13. ### joeyd999 AAC Fanatic!

Jun 6, 2011
3,119
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Wow. Perhaps you can show some math resulting in a unitless moment?

Papabravo likes this.
14. ### Papabravo Expert

Feb 24, 2006
11,163
2,186
A dimensionless moment would truly be some interesting "New Physics". I'm waiting with baited breath to hear more!

15. ### lomax1 Thread Starter New Member

Feb 6, 2014
27
0
What is the meaning of your existence?