question_answer

The moment of inertia of a disc of mass m and radius R about an axis, which is tangential to the circumference of the disc and parallel to its diameter is

A)                 \[{{m}^{3}}\]                     

B)                 \[{{m}^{3}}\]

C)                 \[{{m}^{3}}\]                     

D)                 \[{{m}^{3}}\]

Correct Answer: C

Solution :

                Key Idea: Use parallel axes theorem. From the theorem of parallel axes, the moment of inertia (I) of a body about given axis is equal to its moment of inertia I about  its diameter, plus the product of  the mass m of the body and  square    of    perpendicular      distance between the two axes. That is                                 \[{{v}_{p}}=2{{v}_{e}}=2\times 11.2\]                 \[=22.4km/s\]