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Friday, 9 October

JEE Main 2020 · PhysicsMultiple choiceSingle correctMediumApplication

JEE Main 8 January 2020, Shift 1, Physics Q2

Question 2 of 75 in this shift, Physics question 2 of 25, Section A.

A particle of mass m is fixed to one end of a light spring having force constant k and unstretched length ll. The other end is fixed. The system is given an angular speed ω\omega about the fixed end of the spring such that it rotates in a circle in gravity free space. Then the stretch in the spring is :
  1. (1)mlω2k+mω2\frac{ml\omega^2}{k+m\omega^2}
  2. (2)mlω2k−mω2\frac{ml\omega^2}{k-m\omega^2}Official answer
  3. (3)mlω2k+mω\frac{ml\omega^2}{k+m\omega}
  4. (4)mlω2k−ωm\frac{ml\omega^2}{k-\omega m}

Official answer

Option 2

NTA final key (Jan 2020).