CENTER OF MASS

 Center of gravity is also called center of mass, which is the point of average mass distribution of an object. An object in outer space, where gravity forces are practically zero, has a center of mass, but no center of gravity. For every object, we can use the terms center of gravity and center of mass interchangeable.
Problem:

A beam has a length of 7.8 m and a mass of 44 g that acts at its center. A mass of 200 g like the one in the above diagram is added. Where is the new CM of the system located?

Solution:

This problem again is a simple matter of plugging the values into the center of mass formula. We must make sure however to get all mass values into Newtons before solving.
x = (W1x1 + W2x2 + ….) / (W1 + W2 +….)
x = (1.96 N)(7.8 m) + (0.044 N)(3.9 m) / (2.004 N)
x = 7.7 m