Assertion and Reason on Kepler’s Laws – Rankers Physics

Keplers Law: Practice Problem & Solution

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Angular momentum conservation can be used to explain Kepler's second law of planetary motion. Reason (R): Areal velocity of a planet revolving around the sun is equal to its angular momentum. In the light of the above statements, choose the correct answer from the options given below:
Both (A) and (R) are true and (R) is the correct explanation of (A)
Both (A) and (R) are true but (R) is not the correct explanation of (A)
(A) is true but (R) is false
Both (A) and (R) are false

Short Solution (Best for NEET):

To solve this problem, we apply the core principles of Keplers Law. Understanding the underlying formula is key to arriving at the correct answer below:

Assertion (A) is true because Kepler's second law represents the conservation of angular momentum. Reason (R) is false because areal velocity is \(\frac{dA}{dt} = \frac{L}{2m}\), which is proportional to angular momentum \(L\) but not equal to it.

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