Q. A solid circular disc of mass 50kg rolls along a horizontal floor so that its center of mass has a speed of 0.4 m/s. The absolute value of work done on the disc to stop it is _______ J.
(jee mains 2024)Ans:- (6)
Here, we will use the Work-Energy Theorem:
\[
W = \Delta KE = 0 - \left( \frac{1}{2} mv^2 + \frac{1}{2} I \omega^2 \right)
\]
Simplifying,
\[
W = - \left( \frac{1}{2} \times 50 \times 0.4^2 \times \left( 1 + \frac{1}{2} \right) \right)
\]
Absolute work = +6 J
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