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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceSingle correctMediumCalculation

JEE Main 24 February 2021, Shift 2, Physics Q2

Question 2 of 90 in this shift, Physics question 2 of 30, Section A.

A particle is projected with velocity v0v_0 along xx-axis. A damping force is acting on the particle which is proportional to the square of the distance from the origin i.e. ma=−αx2ma = -\alpha x^2. The distance at which the particle stops :
  1. (1)(2v023α)12\left(\frac{2v_0^2}{3\alpha}\right)^{\frac{1}{2}}
  2. (2)(3v022α)12\left(\frac{3v_0^2}{2\alpha}\right)^{\frac{1}{2}}
  3. (3)(3v022α)13\left(\frac{3v_0^2}{2\alpha}\right)^{\frac{1}{3}}Official answer
  4. (4)(2v03α)13\left(\frac{2v_0}{3\alpha}\right)^{\frac{1}{3}}

Official answer

Option 3

NTA final key.

Chapter
Motion in a Straight Line
Topic
Kinematics in 1D
Idea tested
Position-Dependent Acceleration (v dv/dx)

Same idea in other shifts

Asked 5× in all
  1. 2 Apr 2026, Shift 1 · Q28The velocity of a particle is given as v⃗=−xi^+2yj^−zk^\vec v=-x\hat i+2y\hat j-z\hat k m/s. The magnitude of acceleration at point (1,2,4)(1, 2, 4) is…MediumSingle correct
  2. 1 Feb 2024, Shift 2 · Q51A particle initially at rest starts moving from reference point x=0x = 0 along xx-axis, with velocity vv that varies as v=4xv = 4\sqrt{x}…MediumNumerical value
  3. 25 Jul 2022, Shift 2 · Q51A particle is moving in a straight line such that its velocity is increasing at 5 ms−1^{-1} per meter. The acceleration of the particle is…EasyNumerical value
  4. 27 Aug 2021, Shift 1 · Q23If the velocity of a body related to displacement xx is given by v=5000+24xv=\sqrt{5000+24x} m/s, then the acceleration of the body is __________…EasyNumerical value

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.