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Saturday, 31 October

JEE Main 2021 · PhysicsNumerical answerNumerical valueEasyApplication

JEE Main 17 March 2021, Shift 1, Physics Q28

Question 28 of 90 in this shift, Physics question 28 of 30, Section B.

Consider two identical springs each of spring constant k and negligible mass compared to the mass M as shown. Fig. 1 shows one of them and Fig. 2 shows their series combination. The ratios of time period of oscillation of the two SHM is TbTa=x\frac{T_b}{T_a}=\sqrt{x}, where value of xx is __________. (Round off to the Nearest Integer)

The figure, in words

Two vertical spring-mass systems hung from ceilings (hatched lines). Fig 1: one spring with mass M (in a box) hanging from its lower end, labelled T_a. Fig 2: two identical springs one below the other joined in series, with mass M (in a box) hanging from the lower spring, labelled T_b.

Official answer

2

NTA final key.

Chapter
Oscillations
Topic
SHM Equations
Idea tested
Springs in Series

Same idea in other shifts

Asked 4× in all
  1. 31 Jan 2024, Shift 2 · Q54The time period of simple harmonic motion of mass MM in the given figure is παM5k\pi\sqrt{\frac{\alpha M}{5k}}, where the value of α\alpha…MediumNumerical valueHas a figure
  2. 26 Jul 2022, Shift 2 · Q60As per given figures, two springs of spring constants kk and 2k2k are connected to mass mm. If the period of oscillation in figure (a)…MediumNumerical valueHas a figure
  3. 26 Feb 2021, Shift 1 · Q11If two similar springs each of spring constant K1\mathrm{K_1} are joined in series, the new spring constant and time period would be…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.