A disc of radius 2 mathrm{m} and mass 100 mathrm{kg} rolls on a horizontal floor. Its centre of mass

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6.System of Particles and Rotational Motion

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A disc of radius $2\; \mathrm{m}$ and mass $100\; \mathrm{kg}$ rolls on a horizontal floor. Its centre of mass has speed of $20\; \mathrm{cm} / \mathrm{s} .$ How much work is needed to stop it?

A

$3 \mathrm{J}$

B

$30\; \mathrm{kJ}$

C

$2 \;J$

D

$1\; \mathrm{J}$

(NEET-2019)

Solution

$\mathrm{W}_{\mathrm{all}}=\Delta \mathrm{KE}$

$\Rightarrow W=0-\frac{1}{2} m v_{c m}^{2}\left(1+\frac{K^{2}}{R^{2}}\right)$

$\Rightarrow W=-3 \mathrm{J}$

Standard 11

Physics

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