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A planet revolving in elliptical orbit has : (A) a constant velocity of revolution. (B) has the least velocity when it is nearest to the sun. (C) its areal velocity is directly proportional to its velocity. (D) areal velocity is inversely proportional to velocity. (E) to follow a trajectory such that the areal velocity is constant. Choose the correct answer from the options given below :

1. A only
2. D only
3. C only
4. E only

Correct answer: E only

Solution

A planet in an elliptical orbit sweeps out equal areas in equal times, which means its areal velocity remains constant throughout its orbit. This principle is a consequence of Kepler's second law of planetary motion.

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