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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceDiagram basedEasyApplication

JEE Main 25 February 2021, Shift 2, Physics Q7

Question 7 of 90 in this shift, Physics question 7 of 30, Section A.

Two identical springs of spring constant ‘2k’ are attached to a block of mass m and to fixed support (see figure). When the mass is displaced from equilibrium position on either side, it executes simple harmonic motion. The time period of oscillations of this system is :

The figure, in words

A block of mass m between two fixed walls on a horizontal surface, connected to the left wall by a spring labelled 2k and to the right wall by a spring labelled 2k.
  1. (1)2πm2k2\pi\sqrt{\frac{m}{2k}}
  2. (2)2πmk2\pi\sqrt{\frac{m}{k}}
  3. (3)πmk\pi\sqrt{\frac{m}{k}}Official answer
  4. (4)πm2k\pi\sqrt{\frac{m}{2k}}

Official answer

Option 3

NTA final key.

Chapter
Oscillations
Topic
SHM Equations
Idea tested
Springs in Parallel

Same idea in other shifts

Asked 5× in all
  1. 6 Apr 2023, Shift 1 · Q43A mass m is attached to two strings as shown in figure. The spring constants of two springs are K1K_1 and K2K_2. For the frictionless…EasyDiagram basedHas a figure
  2. 25 Jul 2022, Shift 1 · Q39In figure (A), mass '2 m' is fixed on mass 'm' which is attached to two springs of spring constant k. In figure (B), mass 'm' is attached…MediumDiagram basedHas a figure
  3. 24 Feb 2021, Shift 2 · Q7In the given figure, a body of mass M is held between two massless springs, on a smooth inclined plane. The free ends of the springs are…MediumDiagram basedHas a figure
  4. 17 Mar 2021, Shift 2 · Q6Two particles A and B of equal masses are suspended from two massless springs of spring constants K1\mathrm{K_1} and K2\mathrm{K_2}…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. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.