SOLUTION: It's about physics. Can you please help me solve it? Please. Four identical masses of 2.0 kg each are situated at the four corners of a square. A side of the square measures 3.0

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Question 214903: It's about physics. Can you please help me solve it? Please.
Four identical masses of 2.0 kg each are situated at the four corners of a square. A side of the square measures 3.0 m. Find the moment of inertia about an axis passing through the center of the square and perpendicular to its plane.
Thank you in advance..

Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
The moment of inertia is given by:
I+=+mr%5E2 and, since there are four weights of 2kg each, m = 4(2)=8kg.
r is the distance from the point of rotation which is the distance from the center of the square to the corner of the square. This is just half the length of the diagonal.
To find the length of the diagonal (d) of a 3" (s = 3") square, use the Pythagorean theorem:
d+=+sqrt%282s%5E2%29 Substitute s = 3.
d+=+sqrt%282%289%29%29
d+=+sqrt%2818%29
d+=+4.24 but, in this problem, r = d/2, so...
r+=+2.12meters.
The moment of inertia then is:
I+=+mr%5E2 Substitute m = 4(2) = 8 and r = 2.12
I+=+8%282.12%29%5E2
I+=+8%284.5%29
I+=+36