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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 4 August 2021, Shift 2, Physics Q17

Question 17 of 90 in this shift, Physics question 17 of 30, Section A.

A neutron of mass mn\mathrm{m_n} collides against a moderator nucleus of mass 10 mn10\,\mathrm{m_n} at rest. Considering the collision to be one dimensional, the fractional kinetic energy lost by the neutron (f1\mathrm{f_1}) is [Given : The collision is elastic]
  1. (1)0.67
  2. (2)0.33Official answer
  3. (3)0.72
  4. (4)0.38

Official answer

Option 2

NTA final key.

Chapter
Work, Energy and Power
Topic
Collisions
Idea tested
Fractional Kinetic Energy Transfer

Same idea in other shifts

Asked 2× in all
  1. 27 Jun 2022, Shift 1 · Q38What percentage of kinetic energy of a moving particle is transferred to a stationary particle when it strikes the stationary particle of…EasySingle correct

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 108 of the 174 JEE Main shifts held from 2017 to 2026.