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JEE Main 3 August 2021, Shift 1, Physics Q6

Question 6 of 90 in this shift, Physics question 6 of 30, Section A.

As shown in the figure, a string of length ‘

l

' holds a small bob of mass ‘

m

' while suspended from a point `O'. The bob revolves about a vertical line OC passing through the point of suspension on a horizontal circle such that the string always remains inclined to the vertical at an angle '

\alpha

'. The angular frequency of revolution will be -

The figure, in words

A horizontal hatched ceiling line with point O at its middle. From O a solid slanted line labelled l goes down-left to a dot B (bob) at the left end of a horizontal dotted line B---C---A; a dotted slanted line goes from O down-right to A; a solid vertical line from O down to C; angle alpha marked at O between the slanted solid line and the vertical. An ellipse (circle in perspective) through B and A centred on C with arrowheads showing the direction of revolution. A downward arrow at B labelled mg.

(1) $\sqrt{\frac{g}{l\cos\alpha}}$ Official answer
(2) $\sqrt{\frac{g}{l\sin\alpha}}$
(3) $\sqrt{\frac{g}{l\tan\alpha}}$
(4) $\sqrt{\frac{g}{l}}$

Official answer

Option 1

NTA final key.

Chapter: Laws of Motion
Topic: Circular Motion
Idea tested: Conical Pendulum Dynamics

JEE Main 3 August 2021, Shift 1, Physics Q6

Same idea in other shifts