Rotating Disks. Shown in the diagram are 15 identical disks glued together toget
ID: 2092314 • Letter: R
Question
Rotating Disks. Shown in the diagram are 15 identical disks glued together together to form a rod-like shape, whose overall length is L = 1.0000 m whose total mass is M = 150.0 mg . The entire assembly rotates about axis A that runs perpendicular to the central disk and passing through its center of mass. (a) What is the rotational inertia about axis A? (b) Suppose you approximate the arrangement as a solid rod of the same mass M and length L, and estimated the rotational inertia that way. What percentage difference is obtained, with respect to the exact value from part (a)?Explanation / Answer
a)moment of inertia of a body which is solid and continous about an axis is ? d(r)r^2dv where d(r)=density with respect to radius,v is volume of a infinitesimal volume. b) moment of inertia of a disk about the axis perpendicular to it and passing through the centre =(mr^2)/2 after glued together it takes the shape of a cylindrical continous solid rod and its moment of inertia =Mr^2 where m=mass of a disk,M=mass of entire rod Mr^2=150*(10^-3)*(r^2) there wont be much percentage difference between these two because of same mass and same distribution and the difference is the result of very small adhesive used
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