Question

1. Three rings each of mass m and radius r are so placed that they touch each other as shown in the figure. The moment of inertia of the system about [NCERT Pg. 167) the axis OO' is O 10 5 2 (1) 5 m2 ) (2) Emre (4) m (3) 7 m2 4) I mre 2
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Answer 1

Explanation:

Moment of inertia of the upper ring about the axis I

1

=

2

1

mr

2

Moment of inertia of the one of the lower ring about the axis I

2

=

2

1

mr

2

+mr

2

=

2

3

mr

2

Similarly, moment of inertia of the second lower ring about the axis I

3

=

2

3

mr

2

Total moment of inertia of the system about the axis I=I

1

+I

2

+I

3

=

2

7

mr

2

Radius of gyration k=

3m

I

=

6

7

r