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Saturday, 31 October

JEE Main · Physics · System of Particles and Rotational Motion

COM Velocity Conservation

JEE Main asked COM Velocity Conservation 4 times in 4 of the 108 shifts Lumi analysed, in 2021 and 2022. It belongs to Center of Mass, in System of Particles and Rotational Motion (Physics). The longest wait between two years asking it was 1 year. In 2021 and 2022 it came in more than one shift of the same year.

Updated 2026-10-24

Times asked
4
in 4 shifts
Years
2 of 8
First asked
2021
last in 2022
Pattern
Occasional
across the analysed shifts

Questions on this idea a shift, by year

2017–2026. Asked in 2021 and 2022. Years differ in how many shifts Lumi analysed, so each year is scaled to one shift of 25 Physics questions.

00.050.10’170’200.07’210.07’220’230’240’250’26

Raw count: 2017: 0 in 1 shift · 2020: 0 in 12 shifts · 2021: 2 in 24 shifts · 2022: 2 in 24 shifts · 2023: 0 in 12 shifts · 2024: 0 in 18 shifts · 2025: 0 in 8 shifts · 2026: 0 in 9 shifts.

Shift by shift

Each square is one analysed shift, in date order. Open a filled one for that paper.

  • 20260 of 9
  • 20250 of 8
  • 20240 of 18
  • 20230 of 12
  • 20222 of 24
  • 20212 of 24
  • 20200 of 12
  • 20170 of 1

Asked in that shift More than once Not asked

How JEE Main framed it

Numerical value is the usual form. Skill tested: calculation.

  • Centre of mass speed after elastic collision
  • Recoil speed of gun from bullet

Difficulty

Easy 3Medium 1Hard 0

3 of the 4 questions had a numerical answer.

Every question

All 4 questions

From the official JEE Main shift papers, newest first. Open one for the full question, the options and the official answer.

  1. 28 Jun 2022, Shift 1 · Q56A man of 60 kg is running on the road and suddenly jumps into a stationary trolley car of mass 120 kg. Then, the trolley car starts moving…EasyNumerical value
  2. 30 Jul 2022, Shift 2 · Q3A bullet of mass 10 gram is fired with velocity of 100 m/s from the gun of mass 1 kg . Recoil speed of the gun is :EasySingle correct
  3. 25 Jul 2021, Shift 1 · Q21A body of mass 2 kg moving with a speed of 4 m/s. makes an elastic collision with another body at rest and continues to move in the…MediumNumerical value
  4. 31 Aug 2021, Shift 1 · Q24A block moving horizontally on a smooth surface with a speed of 40 ms−1^{-1} splits into two equal parts. If one of the parts moves at 60…EasyNumerical value

Shifts: 25 Jul 2021, Shift 1, 31 Aug 2021, Shift 1, 28 Jun 2022, Shift 1, 30 Jul 2022, Shift 2.

Same topic

Other ideas in Center of Mass

Center of Mass has 13 ideas JEE Main has asked; 5 of them came up in more than one question.

Topic analysisChapter analysisStudy this chapterAll repeated ideas