PhysicsJEE Main 23 Jan 2026, Shift 1·Q2·MCQ·Moderate

Work, Energy and Power · Potential energy and conservation

A small bob A of mass

m

is attached to a massless rigid rod of length 1m pivoted at point P and kept at an angle of

60^\circ

with vertical as shown in figure. At distance of 1m below point P, an identical bob B is kept at rest on a smooth horizontal surface that extends to a circular track of radius R as shown in figure. If bob B just manages to complete the circular path of radius R upto a point Q after being hit elastically by bob A, then radius R is m.

(1) $\dfrac35$
(2) $\dfrac15$
(3) $\dfrac{2+\sqrt3}{5}$
(4) $\dfrac{2-\sqrt3}{5}$

We corrected a printing error in the original paper

Source printed “A small both A”.

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Work, Energy and Power · Potential energy and conservation

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