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Friday, 9 October

JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumMulti-step

JEE Main 8 January 2020, Shift 1, Physics Q4

Question 4 of 75 in this shift, Physics question 4 of 25, Section A.

Consider a uniform rod of mass M = 4m and length ll pivoted about its centre. A mass m moving with velocity vv making angle θ=π4\theta = \frac{\pi}{4} to the rod's long axis collides with one end of the rod and sticks to it. The angular speed of the rod-mass system just after the collision is :
  1. (1)37vl\frac{3}{7}\frac{v}{l}
  2. (2)372vl\frac{3}{7\sqrt{2}}\frac{v}{l}
  3. (3)327vl\frac{3\sqrt{2}}{7}\frac{v}{l}Official answer
  4. (4)47vl\frac{4}{7}\frac{v}{l}

Official answer

Option 3

NTA final key (Jan 2020).

Chapter
System of Particles and Rotational Motion
Topic
Angular Momentum
Idea tested
Collisions with Pinned Rigid Bodies

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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. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.