Q. A rod $AB$ of mass $10kg$ and length $4m$ rests on a horizontal floor with end $A$ fixed so as to rotate it in vertical plane about perpendicular axis passing through $A$. If the work done on the rod is $100\ J$, the height to which the end $B$ be raised vertically above the floor is
A) $1.5\ m$
B) $2.0\ m$
C) $1.0\ m$
D) $2.5\ m$
Explanation
(b) Work done $= mg(h/2)$
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$100 = \frac{10 \times 10 \times h}{2}$
$\Rightarrow h = 2.0\ m$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.