Posted by **lou** on Sunday, March 27, 2011 at 2:43pm.

3 point mass of 4g placed at x=1,3,-6. where should a point fourth mass of 4 gm be placed to make the center of the mass at the orgin?

this what i got : -24+4+12+4x/16=-8+4x/16. this what i did but i didn't get the right answer(which is 2) can someone tell me what is the problem

- center of mass -
**sean**, Friday, October 14, 2011 at 6:46pm
to find the center of mass, you add up all of the x-points * all of their corresponding masses. (e.g. sum x*m)

and you divide it by the sum of all of the masses (e.g. sum m)

therefore (sum x*m)/(sum m).

you are looking for where to place x to make the center of mass at the origin.

so (1*4)+(3*4)+(-6*4)+(x*4) = 0

solve for x.

-8 = (x*4)

x = 2

TahDah!!

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