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Two unequal masses m and 2m are attached to a thin bar of negligible mass that r

ID: 2197414 • Letter: T

Question

Two unequal masses m and 2m are attached to a thin bar of negligible mass that rotates about an axis perpendicular to the bar. When m is a distance 2d from the axis and 2m is a distance d from the axis, the moment of inertia of this combination is I.

. . . . . Two unequal masses m and 2m are attached to a thin bar of negligible mass that rotates about an axis perpendicular to the bar. When m is a distance 2d from the axis and 2m is a distance d from the axis, the moment of inertia of this combination is I. If the masses are now interchanged, the moment of inertia will be 2/3I . I . 3/2I . 2I . 4I .

Explanation / Answer

a)I1=mr2=m(2d)^2=4md^2 I2=2m(d)^2=2md^2 I=I1+I2=6md^2 b)I1=md^2 I2=2m(2d)^2=8md^2 I new=9md^2 I new=3/2I so option 3 is correct