Question

A disc is hanging from pin as shown in figure and displaced slightly. Then its time period

• A. $T=2\pi \sqrt{\frac{2R}{g}}$
• B. $T=2\pi \sqrt{\frac{3R}{2g}}$
• C. $T=2\pi \sqrt{\frac{R}{2g}}$
• D. $T=2\pi \sqrt{\frac{R}{g}}$

Answer 1

The correct option is B $T=2\pi \sqrt{\frac{3R}{2g}}$

REF. Image

I about an axis passing through

the centre $t^{en}$ do the plane = $\frac{M{R}^2}{2}$

But the line from when oscillation occure is at

a distance R parallel to axis passing through centre

M.I about $AB=\frac{M{R}^2}{2}+M{R}^2$

$I_{AB}=I_{CP}+M{R}^2$

$I_{AB}=\frac{3M{R}^2}{2}$

$T=2\pi \sqrt{\frac{I}{MgR}}=2\pi \sqrt{\frac{3M{R}^2/2}{MgR}}=2\pi \sqrt{\frac{3R}{2g}}$