Center of Mass and Moment of Inertia

[sealedhuman77]

Homework Statement

Find the center of mass of the collection of mass points in Figure P.12 and then find the moment of inertia of the system about an axis through the center of mass and parallel to the y-axis.

Homework Equations

Center of Mass
Moment of Inertia

The Attempt at a Solution

M1 = 1kg, r1 = (1i + 0j) m
M2 = 2kg, r2 = (4i + 0j) m
M3 = 3kg, r3 = (6i + 0j) m
Mass total = 6kg

X of CM = 1/6 (0 + 8 + 18) = 13/3 m
Y of CM = 1/6 (0 + 0 + 0) = 0 m

I = mR$$^{2}$$
I = 6 (4.333)$$^{2}$$
I = 112.6667 kgm$$^{2}$$

The answer was wrong. Thanks for the help

 

[sealedhuman77]

moving it up

 

[sealedhuman77]

moving it up again

 

[nickclarson]

I wouldn't keep bumping this thread until your attachment has been approved. ;)