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NEET PHYSICSMedium

A disc of radius 2 m2\text{ m} and mass 100 kg100\text{ kg} rolls on a horizontal floor. Its centre of mass has speed of 20 cm/s20\text{ cm/s}. How much work is needed to stop it?

1

3 J3\text{ J}

2

30 kJ30\text{ kJ}

3

2 J2\text{ J}

4

1 J1\text{ J}

Step-by-Step Solution

Work required = change in kinetic energy. Final KE = 0. Initial KE = 12mv2+12Iω2=34mv2=34×100×(20×10−2)2=3 J\frac{1}{2}mv^2 + \frac{1}{2}I\omega^2 = \frac{3}{4}mv^2 = \frac{3}{4} \times 100 \times (20 \times 10^{-2})^2 = 3\text{ J}. ∣ΔKE∣=3 J|\Delta KE| = 3\text{ J}.

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