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Saturday, 31 October

JEE Main 2021 · PhysicsNumerical answerNumerical valueMediumCalculation

JEE Main 25 July 2021, Shift 1, Physics Q25

Question 25 of 90 in this shift, Physics question 25 of 30, Section B.

A particle of mass 'mm' is moving in time 'tt' on a trajectory given by r⃗=10αt2i^+5β(t−5)j^\vec{r}=10\alpha t^2\hat{i}+5\beta(t-5)\hat{j} Where α\alpha and β\beta are dimensional constants. The angular momentum of the particle becomes the same as it was for t=0t=0 at time t=t=_________ seconds.

Official answer

10

NTA final key.

Chapter
System of Particles and Rotational Motion
Topic
Angular Momentum
Idea tested
Angular Momentum of Particle

Same idea in other shifts

Asked 3× in all
  1. 2 Apr 2026, Shift 1 · Q29The position of an object having mass 0.10.1 kg as a function of time tt is given as r⃗=(10t2i^+5t3j^)\vec r=\left(10t^2\hat i+5t^3\hat j\right) m. At…MediumOther
  2. 28 Jun 2022, Shift 1 · Q55The position vector of 1 kg object is r⃗=(3i^−j^)\vec{r} = \left(3\hat{i} - \hat{j}\right) m and its velocity…EasyNumerical value

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. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.