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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 17 March 2021, Shift 2, Physics Q17

Question 17 of 90 in this shift, Physics question 17 of 30, Section A. NTA dropped this question from the final key; it is left out of every count on this site.

A block of mass 1 kg attached to a spring is made to oscillate with an initial amplitude of 12 cm. After 2 minutes the amplitude decreases to 6 cm. Determine the value of the damping constant for this motion. ( take ln⁡2=0.693\ln 2=0.693 )
  1. (1)1.16×102 kg s−11.16\times10^{2}\ \mathrm{kg\ s^{-1}}
  2. (2)0.69×102 kg s−10.69\times10^{2}\ \mathrm{kg\ s^{-1}}
  3. (3)5.7×10−3 kg s−15.7\times10^{-3}\ \mathrm{kg\ s^{-1}}
  4. (4)3.3×102 kg s−13.3\times10^{2}\ \mathrm{kg\ s^{-1}}

Official answer

Dropped by NTA (marks given to all)

NTA final key: NTA final key 'D' = question dropped.

Chapter
Oscillations
Topic
SHM Equations
Idea tested
Damped Amplitude Decay

Same idea in other shifts

Asked 1× in all
  1. 16 Mar 2021, Shift 2 · Q6Amplitude of a mass-spring system, which is executing simple harmonic motion decreases with time. If mass = 500 g, Decay constant = 20 g/s…MediumSingle 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.