question_answer

The moment of inertia of a circular disc of radius 2 m and mass 2 kg, about an axis passing through its centre of mass is \[2\text{ }kg-{{m}^{2}}.\] Its moment of inertia about an axis parallel to this axis and passing through its edge (in \[2\text{ }kg-{{m}^{2}}.\]) is

A)  10         

B)  8

C)  6                                            

D)  4            

Correct Answer: A

Solution :

                 Moment of inertia about\[XX,\] \[{{I}_{XX}}=2kg-{{m}^{2}}\] Moment of inertia about the given axis ie, about\[\,YY\], \[{{I}_{\,YY}}={{I}_{XX}}+M{{R}^{2}}\] \[=2+2\times {{(2)}^{2}}\] \[=2+8\] \[=10\,kg-{{m}^{2}}\]