# Thread: One question regarding moment??

1. ## One question regarding moment??

Hi,

I am doing a project which need the semimajor axis value. I only have moment variables: m00,m01,... mu01, mu11.... Any friend can tell me what is the use of the moment variables? And how to use these variables to compute the semimajor axis value? Thanks!

Regards,
Alexander

2. ## Physics????

I have a vague memory that this has something to do with physics or dynamics.... You may need some more information from whomever gave you this assignment/task. Do you have a physics or dynamics book? (I don't have one with me.)

3. Do you mean momentum?

4. Originally Posted by CornedBee
Do you mean momentum?
The principle of moments is derived from Archimedes' discovery of the operating principle of the lever. Archimedes was a Greek mathematician and physicist noted for his work in hydrostatics and mechanics and geometry (287-212 BC).

With a lever, one applies a force, in his day most often human muscle, to an arm, a beam of some sort. Archimedes noted that the amount of force applied to the object, the moment of force, is defined as M = rF, where F is the applied force to the lever, and r is the distance from the applied force to the object.
http://www.absoluteastronomy.com/enc..._(physics).htm