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Saturday, 31 October

JEE Main 2020 · PhysicsNumerical answerNumerical valueMediumMulti-step

JEE Main 9 January 2020, Shift 1, Physics Q22

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

One end of a straight uniform 1 m long bar is pivoted on horizontal table. It is released from rest when it makes an angle 30∘30^{\circ} from the horizontal (see figure). Its angular speed when it hits the table is given as n s−1\sqrt{n}\ \mathrm{s^{-1}}, where n is an integer. The value of n is __________.

The figure, in words

A table drawn as a rectangle outline with an open bottom. A dot on the table's top edge near the left marks the pivot, with a straight line (the bar) rising to the upper right. An angle arc labelled 30 sits between the bar and the table top, and a curved arrow with an arrowhead points downward at the right of the label.

Official answer

15.00

NTA final key (Jan 2020).

Chapter
System of Particles and Rotational Motion
Topic
Moment of Inertia
Idea tested
MOI of Standard Shapes

Same idea in other shifts

Asked 5× in all
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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.