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Friday, 9 October

JEE Main 2020 · PhysicsMultiple choiceDiagram basedMediumMulti-step

JEE Main 2 September 2020, Shift 1, Physics Q5

Question 5 of 75 in this shift, Physics question 5 of 25.

A uniform cylinder of mass MM and radius RR is to be pulled over a step of height aa (a<Ra < R) by applying a force FF at its centre 'O' perpendicular to the plane through the axes of the cylinder on the edge of the step (see figure). The minimum value of FF required is :

The figure, in words

Cylinder of radius R with centre O resting on the ground against a step of height a; force F applied at O directed up and to the right, perpendicular to the line from the step edge to O.
  1. (1)MgaRMg\frac{a}{R}
  2. (2)Mg1−(R−aR)2Mg\sqrt{1-\left(\frac{R-a}{R}\right)^{2}}Official answer
  3. (3)Mg1−a2R2Mg\sqrt{1-\frac{a^{2}}{R^{2}}}
  4. (4)Mg(RR−a)2−1Mg\sqrt{\left(\frac{R}{R-a}\right)^{2}-1}

Official answer

Option 2

NTA final key (Sep 2020).

Chapter
System of Particles and Rotational Motion
Topic
Torque and Equilibrium
Idea tested
Cylinder Over a Step Problem

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Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.