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Saturday, 31 October

JEE Main 2021 · PhysicsMultiple choiceDiagram basedMediumApplication

JEE Main 24 February 2021, Shift 2, Physics Q7

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

In 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 attached to firm supports. If each spring has spring constant kk, the frequency of oscillation of given body is :

The figure, in words

An inclined plane rising to the right at angle alpha (marked at the bottom-left, with a horizontal base line). A block labelled M sits on the incline between two springs, each labelled k: the lower spring is attached to a hatched support at the bottom-left end of the incline and the upper spring is attached to a hatched support at the upper-right end.
  1. (1)12πkMgsin⁡α\frac{1}{2\pi}\sqrt{\frac{k}{Mg\sin\alpha}}
  2. (2)12π2kMgsin⁡α\frac{1}{2\pi}\sqrt{\frac{2k}{Mg\sin\alpha}}
  3. (3)12π2kM\frac{1}{2\pi}\sqrt{\frac{2k}{M}}Official answer
  4. (4)12πk2M\frac{1}{2\pi}\sqrt{\frac{k}{2M}}

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. 25 Feb 2021, Shift 2 · Q7Two identical springs of spring constant ‘2k’ are attached to a block of mass m and to fixed support (see figure). When the mass is…EasyDiagram 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.