integrating to find the balance point.

[Fred_Kohlhepp]

I don't understand why the first moment of integration doesn't balance the beam.

Anybody?

[ValeryOchkov]

Sorry, I do not see any problem - see the attach

[Fred_Kohlhepp]

The first number (17.056 in) is the balance point, if you pick it up there it won't tip. I was mistakenly assuming that was where half the mass was on one side and half on the other; that will only be true for a symmetrical arrangement.

Need to be careful which point you want.

[Werner_E]

Fred Kohlhepp wrote:

The first number (17.056 in) is the balance point, if you pick it up there it won't tip. I was mistakenly assuming that was where half the mass was on one side and half on the other; that will only be true for a symmetrical arrangement.

Need to be careful which point you want.

Yes, but I was puzzled, too, when I first glanced over your sheet.

You get equality if you take in account the distance from the centroidal axis:

[Fred_Kohlhepp]

Yes, the weight moments balance, but the weight does not. That's where I was getting confused.

Trying to do vibration of a non-uniform beam, solve for natural frequencies. Rayleigh method needs a shape function, I thought, "balance the beam at it's CG." and got lost on where the CG was when the weight on one side was more than on the other.

[ValeryOchkov · Accepted solution]

Sorry,

It is my KnowHow (a brend) to point "Correct answer" on one own answer

[RichardJ]

You are using Prime?

[ValeryOchkov]

Richard Jackson wrote:

You are using Prime?

Why not!

[Fred_Kohlhepp]

Kicking and screaming!

Actually 3.0 is good enough to do useful (simple, but useful) work. And it's not going to go away; might as well start up the new editor learning curve--retirement is too far away!

[RichardJ]

Actually 3.0 is good enough to do useful (simple, but useful) work.

True. The reason I don't do that though is that I can't reuse anything I create in something less simple that Prime can't handle. Or if the problem turns out to be less simple than first thought, then I would have to type everything into MC15 again, because I can't convert backwards.

[Fred_Kohlhepp]

I feel the same way! But we've got "newbies" coming in; is it fair to have them learn 15 when it's going away in 2(?) years?

And it's embarrassing when you have to have help to edit their mistakes because you don't know the editor! I need to get far enough to be dangerous!

[RichardJ]

I feel the same way! But we've got "newbies" coming in; is it fair to have them learn 15 when it's going away in 2(?) years?

They are newbies, so what has "fair" got to do with it? Make them use a typewriter and a slide rule for their first three months. It will make appreciate the wisdom of their elders

[Fred_Kohlhepp]

LOL

I showed them a slide rule; they didn't know what it was. And I can't find a typewriter!

If I make Mathcad too difficult they just demand MatLab.

But I like the way you think!