Question

The temperature of a thin uniform circular disc, of diameter 1m is increased by 10⁰C. The percentage increase in its moment of inertia about an axis passing through its centre and perpendicular to its surface is - (a = 11 × 10^–6 / ŗC)

• A. 0.0055 %
• B. 0.011%
• C. 0.022%
• D. 0.044%

Answer 1

Answer: (C)

0.022%

Answer 2

I = $\frac{1}{2}$mr²

lnI = ln$\frac{1}{2}$m + ln r²

ln I = 2ln r + ln$\frac{1}{2}$m

$\frac{\Delta I}{I}$= 2 $\frac{\Delta r}{r}$= 2 a Dq

= 2 × 11 × 10^–6 × 10

= 22 × 10^–5 = 22 × 10^–3 % = 0.022%