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Saturday, 31 October

JEE Main 2025 · PhysicsNumerical answerNumerical valueMediumMulti-step

JEE Main 8 April 2025, Shift 2, Physics Q47

Question 47 of 75 in this shift, Physics question 22 of 25, Section B.

A thin solid disk of 1 kg is rotating along its diameter axis at the speed of 1800 rpm. By applying an external torque of 25π25\pi Nm for 40s, the speed increases to 2100 rpm. The diameter of the disk is __________ m.

Official answer

40

NTA final key.

Chapter
System of Particles and Rotational Motion
Topic
Angular Momentum
Idea tested
Angular Impulse-Momentum Theorem

Same idea in other shifts

Asked 2× in all
  1. 1 Feb 2024, Shift 1 · Q31The dimensional formula of angular impulse is :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. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.