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(8%) Problem 11: A uniform flat disk of radius R and mass 2M is pivoted at point

ID: 1791099 • Letter: #

Question

(8%) Problem 11: A uniform flat disk of radius R and mass 2M is pivoted at point P. A point mass of 1/2 M is attached to the edge of the disk. 2M M otheexpertta.com 33% Part (a) Calculate the moment of inertia ICM of the disk (without the point mass) with respect to the central axis of the disk, in terms of M and R 33% Part (b) Calculate the moment of inertia IP of the disk (without the point mass) with respect to point P in terms of M and R Calculate the total moment of inertia /T of the disk with the point mass with respect to point P 33% Part (c) in terms of M and R Grade Summary Deductions Potential IT 0% 100%

Explanation / Answer

a)

Icm = moment of inertia of disk about the COM = (0.5) (2M) R2 = M R2

b)

d = distance of P from center = R

using parallel axis theorem

Ip = Icm + (2M) d2 = M R2 + (2M) R2 = 3  M R2

c)

IT = Ip + (M/2) (2R)2

IT = 3  M R2 + 2 M R2 = 5 M R2