# Center of Mass

Written by Jerry Ratzlaff on . Posted in Relativity

Center of mass or center of gravity is a specific point in a system in reference to a mass. The center of mass of a rigid object is a fixed point in relationship to the mass.

## formula

A system at a specific time, on the same axis, having two masses.

$$x_{cm} = \frac {m_1 x_1 \;+\; m_2 x_2 } {m_1 \;+\; m_2}$$

Where:

$$x_{cm}$$ = center of mass

$$m_1$$ = mass 1

$$m_2$$ = mass 2

$$x_1$$ = position 1

$$x_2$$ = position 2

## formula

A system at a specific time, on the same axis, having multiple masses.

$$x_{cm} = \frac {m_1 x_1 \;+\; m_2 x_2 \;+\; \;\cdots } { m_1 \;+\; m_2 \;+\; \;\cdots }$$

Where:

$$x_{cm}$$ = center of mass

$$m_1$$ = mass 1

$$m_2$$ = mass 2

$$x_1$$ = position 1

$$x_2$$ = position 2