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OrlandoLewis
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Homework Statement
The shows an arrangement of 15 identical disks that have been glued together in a rod-like shape of length L = 1.0000 m and (total) mass M = 100.0 mg. The disks are uniform, and the disk arrangement can rotate about a perpendicular axis through its central disk at point O. (a) What is the rotational inertia of the arrangement about that axis? (b) If we approximated the arrangement as being a uniform rod of mass M and length L, what percentage error would we make in calculating the rotational inertia?
M = 100.0 mg = 1×10-4 kg
L = 1.0000 m
# of disks = 15
Homework Equations
Inertia of a disk about a central diameter
I = (MR2)/2
Inertia of set of particles
I = ∑miri2
The Attempt at a Solution
Itotal = (MR2)/4 + ∑miri2
Itotal = ML2 / 4⋅302 + (2M/15)(1 + 4 + 9 + 16 + 25 + 36 + 49)(L/15)
Itotal = 8.298 kg - m2
Did I have the right solution?
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