Question

What must be the relation between length 'L' and radius 'R' of the cylinder if its moment of inertia about its axis is equal to that about the equatorial axis ?

• A. L = R
• B. L = 2R
• C. L = 3R
• D. L = $\sqrt{3}$R

Answer 1

Answer: (D)

L = $\sqrt{3}$R

Answer 2

$\frac{mR^{2}}{2}$ = M $\left( \frac{L^{2}}{12} + \frac{R^{2}}{4} \right)$

or $\frac{R^{2}}{2}$= $\frac{L^{2}}{12}$+ $\frac{R^{2}}{4}$

or L = $\sqrt{3}$R