« previous next »
Pages: 1 [2] 3  All |   Go Down

Author Topic: Math Formula Needed  (Read 5400 times)

0 Members and 1 Guest are viewing this topic.

ronjonp

  • Needs a day job
  • Posts: 7529
Re: Math Formula Needed
« Reply #15 on: November 04, 2008, 05:28:26 PM »
Quote from: Atook on November 04, 2008, 05:26:45 PM
Stress will be the tension in lbs divided by the cross sectional area of the rod.

And Port is right, my solution was for the drawing shown. Port's solution can be used for other triangles, just substitute your H & W values.

My solution stayed away from trig (sort of) and is:

 T=W*L/H

Where T=tension in lbs, W= load, L=length of hypotenuse, and H=height.

Nerd  :-D
Logged

Windows 11 x64 - AutoCAD /C3D 2023
Custom Build PC

CAB

  • Global Moderator
  • Seagull
  • Posts: 10401
Re: Math Formula Needed
« Reply #16 on: November 04, 2008, 05:40:18 PM »
I understand now.

I love this stuff :roll:
Logged
I've reached the age where the happy hour is a nap. (°¿°)
Windows 10 core i7 4790k 4Ghz 32GB GTX 970
Please support this web site.

CAB

  • Global Moderator
  • Seagull
  • Posts: 10401
Re: Math Formula Needed
« Reply #17 on: November 04, 2008, 05:49:53 PM »
I was trying to get the formula in a LISP form but don't know what to do with the -1 power.
Code: [Select]
(/ load (sin(tan (/ H W))))Hight & Width
Logged
I've reached the age where the happy hour is a nap. (°¿°)
Windows 10 core i7 4790k 4Ghz 32GB GTX 970
Please support this web site.

jnieman

  • Guest
Re: Math Formula Needed
« Reply #18 on: November 04, 2008, 05:56:36 PM »
I'm sticking with my reply :P
Logged

Strucmad

  • Guest
Re: Math Formula Needed
« Reply #19 on: November 04, 2008, 05:56:49 PM »
tan-1 is the inverse tan or (arctan)

found this it might help. (note radians)

http://www.afralisp.net/Tips/code20.htm
Logged

Strucmad

  • Guest
Re: Math Formula Needed
« Reply #20 on: November 04, 2008, 06:00:22 PM »
CAB
sorry mate a man of your experience would know the (radians) thing....
I didn't need to point that one out.. :oops:
Logged

Spike Wilbury

  • Guest
Re: Math Formula Needed
« Reply #21 on: November 04, 2008, 06:06:52 PM »
Quote from: CAB on November 04, 2008, 05:49:53 PM
I was trying to get the formula in a LISP form but don't know what to do with the -1 power.
Code: [Select]
(/ load (sin(tan (/ H W))))Hight & Width

just in case - load is a lisp function - ..... :)
Logged

Atook

  • Swamp Rat
  • Posts: 1029
  • AKA Tim
Re: Math Formula Needed
« Reply #22 on: November 04, 2008, 06:24:47 PM »
CAB, my equation is the same as Port's, just without any trig functions (you could say they've been evaluated already).

SohCahToa right? :)
Logged

Strucmad

  • Guest
Re: Math Formula Needed
« Reply #23 on: November 04, 2008, 06:39:13 PM »
Atook, your right there.

CAB just divide the hypotenuse by the height and multiply by load

Code: [Select]
(* load (/  (sqrt (+ (* h h) (*w w))) h))
I'm not good at lisp, someone might need to check the syntax  :oops:
Logged

CAB

  • Global Moderator
  • Seagull
  • Posts: 10401
Re: Math Formula Needed
« Reply #24 on: November 04, 2008, 06:55:14 PM »
Thanks Luis I just threw the load in there at the posting  for readability.
PS_Port, Arctan I understand but did not recognize it as tan-1
This works just fine.
Code: [Select]
_$ (setq l 500 h 35.5 w 54.5)(* l (/  (sqrt (+ (* h h) (* w w))) h))
916.089
« Last Edit: November 04, 2008, 06:59:32 PM by CAB »
Logged
I've reached the age where the happy hour is a nap. (°¿°)
Windows 10 core i7 4790k 4Ghz 32GB GTX 970
Please support this web site.

Strucmad

  • Guest
Re: Math Formula Needed
« Reply #25 on: November 04, 2008, 06:57:44 PM »
Cool bananas

I get thrown with arctan  :-D
Logged

CAB

  • Global Moderator
  • Seagull
  • Posts: 10401
Re: Math Formula Needed
« Reply #26 on: November 04, 2008, 07:04:51 PM »
This works as well.  8-)
Code: [Select]
(/ 500(sin(atan (/ 35.5 54.5))))
916.089

So here is the final test.
Code: [Select]
Where T=tension in lbs, W= load, L=length of hypotenuse, and H=height.

(setq W 500 H 35.5 L 54.5)

(setq T (/ W (sin (atan (/ L H)))))
916.089

(setq T (* W (/  (sqrt (+ (* H H) (* L L))) H)))
916.089
« Last Edit: November 04, 2008, 07:11:27 PM by CAB »
Logged
I've reached the age where the happy hour is a nap. (°¿°)
Windows 10 core i7 4790k 4Ghz 32GB GTX 970
Please support this web site.

Bob Garner

  • Guest
Re: Math Formula Needed
« Reply #27 on: November 04, 2008, 08:26:48 PM »
My company wouldn't let us use the net today (!?).  I'm finally home from a really long day and not presently capable of doing any math at all so I'm worthless.  But looks like everyone's covered it well.  All day I had that song on my mind, "Whiskey for my horses, champaigne for my men".  After reading all your posts, I'm singing, "Whiskey for my horses, Pay raises for the Swampers". 
Kips are in units of 1000 pounds or one kip = one thousand pounds.  Anybody know who the hell Kip is?

Happy evening all.  May your votes work out for you.

Bob
Logged

CAB

  • Global Moderator
  • Seagull
  • Posts: 10401
Re: Math Formula Needed
« Reply #28 on: November 04, 2008, 10:10:04 PM »
Bob,
Hope tomorrow is a better one. 8-)
Logged
I've reached the age where the happy hour is a nap. (°¿°)
Windows 10 core i7 4790k 4Ghz 32GB GTX 970
Please support this web site.

Notsober

  • Guest
Re: Math Formula Needed
« Reply #29 on: November 04, 2008, 10:32:53 PM »
Quote from: Bob Garner on November 04, 2008, 08:26:48 PM
Anybody know who the hell Kip is?

yes. Kip is that burned-out engineer who needs help with his "engineering" from a guy named Robert that just so happens to be gifted with pointing out all of his mistakes.

Dr. George: "Good catch, Robert, wow! **makes sounds of a crowd screaming**

I need to make a youtube video of the engineer here... y'all would laugh your (_Y_)'s off!
Logged
Pages: 1 [2] 3  All |   Go Up
« previous next »