Inertia units conversion 4

[bpelec]

I feel as though this may have been explained before, but my searching was not successful. My apologies if I have missed the answer...

I am an electrical engineer struggling with the units of inertia.

I have a specification that states that the inertial load is 0.65 lb-in-sec^2. I can't think of inertia in those units, and so I want to convert to kg-m^2.

I have found several online calculators that can perform this conversion. Here are two:

http://www.magtrol.com/support/inertia_calc.htm

http://www.linengineering.com/LinE/contents/stepmotors/Calculator.aspx

So, all seems good, but I can't work out how on earth the conversion is happening without any additional information given the change in units.

My question is this: what is the theory behind converting an inertia from lb-in-sec^2 to kg-m^2?

Many thanks,

BPELEC.

 

[IRstuff]

That's why Mathcad is my primary tool, since any error in force vs. mass will show up in the units.

TTFN

FAQ731-376

 

[rob768]

try this little program. it does the job converting to international units quite well. Ashame it is still needed

http://www.katmarsoftware.com/uconeer.htm

 

[katmar]

swearingen, I share your aversion for the lbm and kgf units but unfortunately kgf was/is very widely used in European texts (and engineering practice) and the lbm is probably the most widely used unit of mass ever conceived. This ongoing problem with units was why I wrote the Uconeer program kindly plugged by rob768 above. As an indication of the need for this sort of program, Uconeer averages about 4000 downloads per month, and it is only one of dozens of unit conversion programs available.

Harvey

Katmar Software
Engineering & Risk Analysis Software

http://katmarsoftware.com

 

[rob768]

your little program is much appreciated..