Question

If the moment of inertia of a disc about an axis tangential and paralled to its surface be I, then what will be the moment of inertia about the axis tangential but perpendicular to the surface:

• A. 6/5 I
• B. 3/4 I
• C. 3/2 I
• D. 5/4 I.

Answer 1

Answer: (A)

6/5 I

Answer 2

M.I. of disc about tangent in a plant

$= \frac { 5 } { 4 } m R ^ { 2 }$= I

$\therefore m R ^ { 2 } = \frac { 4 } { 5 } I$

M.I. of disc about tangent to plane

Substituting the value of mR2 from equation (i) we get