| Be Excellent To Each Other https://www.beexcellenttoeachother.com/forum/ |
|
| Maths! https://www.beexcellenttoeachother.com/forum/viewtopic.php?f=3&t=10598 |
Page 1 of 1 |
| Author: | Mimi [ Fri Oct 30, 2015 18:25 ] |
| Post subject: | Maths! |
OK, so I need MATHS to illustrate something I am working on. Basically the difference in circumference (or perimeter) in square and round needles of equivalent size when measured through a standard needle gauge (which is given in mm diameter) so the widest point of each will be the diameter of the round needle and the diagonal of the square needle (being the widest point). I'm pretty sure the maths is sound, what I really am not sure of is if I have rendered the calculation properly: I've basically forgotten how to write simple equations. Attachment: circ vs peri.jpg Is that right? Specifically the second. |
|
| Author: | Mr Dave [ Fri Oct 30, 2015 18:38 ] |
| Post subject: | Re: Maths! |
The second is right, but not how I'd have done it (4 * 8 * cos (45deg)) = 22.6274 |
|
| Author: | Mimi [ Fri Oct 30, 2015 18:45 ] |
| Post subject: | Re: Maths! |
Ah, fair enough, but at least that shows it is right. I was pretty certain the result was right and I think everyone knows Pythagoras at least. What I wasn't sure of was if I'd actually written the equation properly (I know I don't need the multiplication symbol in there, but thought it made it clearer to those of us who have forgotten how maths works 
|
|
| Author: | BikNorton [ Fri Oct 30, 2015 22:10 ] |
| Post subject: | Re: Maths! |
I know it's is semantics but it looks really.wrong to write the circumference like that instead of 2πr. Besides that, would showing the (larger) difference in area not be more useful? |
|
| Author: | Mimi [ Fri Oct 30, 2015 22:37 ] |
| Post subject: | Re: Maths! |
BikNorton wrote: I know it's is semantics but it looks really.wrong to write the circumference like that instead of 2πr. Though 2πr is correct and absolutely the standard form, a needle gauge when working with round needles measures the diameter, so to make this representative in the calculation as displayed I'd have to halve the diameter to give the radius to then multiply again to fit the form, which doesn't make any sense. Quote: Besides that, would showing the (larger) difference in area not be more useful? Not for what I am using it for. Yarn wraps around the diameter or perimeter of the needle, rather than occupy the space within it, so it is the difference in the distance the yarn has to travel around the needle that has to be accounted for when sizing the needle for the task. |
|
| Author: | BikNorton [ Fri Oct 30, 2015 22:56 ] |
| Post subject: | Re: Maths! |
Oh yeah, there's another kind of needle than the ones I get stabbed by. I can stop being freaked out by the possibility of someone using a square one now. |
|
| Author: | Mimi [ Fri Oct 30, 2015 23:31 ] |
| Post subject: | Re: Maths! |
BikNorton wrote: Oh yeah, there's another kind of needle than the ones I get stabbed by. I can stop being freaked out by the possibility of someone using a square one now. I'd be freaked out, too, if someone stuck a needle in me that had an 8mm diameter! |
|
| Author: | BikNorton [ Fri Oct 30, 2015 23:47 ] |
| Post subject: | Re: Maths! |
That too I guess! The venesection one is about 2mm and that's quite enough. |
|
| Author: | Mimi [ Fri Oct 30, 2015 23:54 ] |
| Post subject: | Re: Maths! |
2mm? Goodness, that is a hefty bit of metalware  I'm sorry to hear that 
|
|
| Page 1 of 1 | All times are UTC [ DST ] |
| Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group http://www.phpbb.com/ |
|