The

Center of Mass of an object (of mass m) is the single

point that moves in the same way as a point mass (of mass m) would move when subjected to the same

external forces that act on the object. That is, if the

resultant force acting on an object (or system of objects) of mass m is

** F**, the

acceleration of the center of mass of the object (or system) is given by

**a**cm = F/m

If the object is considered to be composed of tiny masses m1, m2, m3, and so on, at coordinates (x1,y1,z1), (x2,y2,z2), and so on, then the coordinates of the center of mass are given by

where **Σ** = sigma, the sequence of

**The x-coordinate**

**X**cm = **Σ**(xi * mi) / **Σ**(mi)

**The y-coordinate**

**Y**cm = **Σ**(yi * mi) / **Σ**(mi)

**The z-coordinate**

**Z**cm = **Σ**(zi * mi) / **Σ**(mi)

where the sums extend over all masses composing the object. In a uniform gravitational field, the center of mass and the center of gravity coincide.

*For the integration method of center of mass, check out Center of Mass: Part Two.*