Question

Assertion: A particle of mass $m$ takes uniform horizontal circular motion inside a smooth funnel as shown. Normal reaction in this case is not $mg\cos \theta$.
Reason: Acceleration of particle is not along the surface of funnel.

• A. Both Assertion and Reason are true and the Reason is correct explanation of the Assertion.
• B. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
• C. Assertion is true, but the Reason is false.
• D. Assertion is false, but the Reason is true.

Answer 1

The correct option is A Both Assertion and Reason are true and the Reason is correct explanation of the Assertion.


From FBD,
$N\cos \theta =mg$
$\Rightarrow N=mg\sec \theta$
and $N\sin \theta =\frac{m{v}^2}{R}$
So, Normal reaction is $mg\sec \theta$

Why this question? Tip: It explain the minimum velocity required to motion of a particle inside the smooth cone.