How do you calculate Center of mass

AI Thread Summary
To calculate the center of mass (COM), the equation used is Cm = sum of MR / sum of masses, where R is the reference point chosen. The reference point can be any mass in the system, and the COM is measured relative to that point. If given x-coordinates, the COM can be found by summing the products of each mass and its x-coordinate, then dividing by the total mass. The x-coordinates must be measured from the selected reference point. Understanding the choice of reference point is crucial for accurate calculations of the center of mass.
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Homework Statement



I'm confused about how to find the center of mass
http://www.screencast.com/users/ntrinh3/folders/Jing/media/a9773d23-38f1-4d28-a6f8-3b681d42d4c2

and

http://www.screencast.com/users/ntrinh3/folders/Jing/media/bfb40c40-0068-41e8-ac83-2146e1df3330

Homework Equations


So the equation my professor gives Cm=sum of MR/sum of masses


The Attempt at a Solution


Where exactly is this R reference point?
 
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You just pick a point, for example if you pick your reference as the 2kg mass, then your COM will be measured from there.
 
oh so that's it.

How about if they just give you the x-coordinate in a system? exe:

http://www.screencast.com/users/ntrinh3/folders/Jing/media/010db89d-7781-4262-aa79-57eaf706730f

do you just add all of the x-coordinates and divide by how many points?
 
MX=m1x1+m2x2+m3x3+...

the 'x's are measured relative to wherever you take your reference point as.
 
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