Physics · 2020
JEE Main · 7 January 2020, Shift 2 · Q4
Mass per unit area of a circular disc of radius a depends on the distance r from its centre as σ( r )= A + Br. The moment of inertia of the disc…
Mass per unit area of a circular disc of radius a depends on the distance r from its centre as $\displaystyle \sigma(\mathrm{r})=\mathrm{A}+\mathrm{Br}$. The moment of inertia of the disc about the axis, perpendicular to the plane and passing through its centre is :
Official answer
(1)
$\displaystyle 2 \pi a^4\left(\frac{A}{4}+\frac{a B}{5}\right)$
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JEE Main 2020 Physics question, with the answer from NTA’s final answer key. Where our answers come from.