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Saturday, 31 October

JEE Main 2025 · PhysicsMultiple choiceSingle correctMediumMulti-step

JEE Main 3 April 2025, Shift 2, Physics Q29

Question 29 of 75 in this shift, Physics question 4 of 25, Section A.

Consider two blocks A and B of masses m1=10m_1 = 10 kg and m2=5m_2 = 5 kg that are placed on a frictionless table. The block A moves with a constant speed v=3v = 3 m/s towards the block B kept at rest. A spring with spring constant k = 3000 N/m is attached with the block B as shown in the figure. After the collision, suppose that the blocks A and B, along with the spring in constant compression state, move together, then the compression in the spring is, (Neglect the mass of the spring)

The figure, in words

Block A (m1 = 10 kg) moving right with speed v toward block B (m2 = 5 kg) on a frictionless table; a spring of constant k = 3000 N/m is attached to the left face of block B.
  1. (1)0.4 m
  2. (2)0.3 m
  3. (3)0.2 m
  4. (4)0.1 mOfficial answer

Official answer

Option 4

NTA final key.

Chapter
Work, Energy and Power
Topic
Collisions
Idea tested
Spring-Mass Impact

Same idea in other shifts

Asked 2× in all
  1. 17 Mar 2021, Shift 2 · Q5Two identical blocks A and B each of mass m resting on the smooth horizontal floor are connected by a light spring of natural length L and…MediumDiagram basedHas a figure

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.