Question

The velocity of a planet is constant throughout its elliptical trajectory in an orbit.

(a) True

(b) False

This question was posed to me by my college professor while I was bunking the class.

My question is from Gravitation in portion Gravitation of Physics – Class 11

Answer 1

Right choice is (b) False

The explanation is: From Kepler’s law of area, we know that a planet sweeps equal areas at equal intervals of time. Therefore, when the planet is closer to the sun it sweeps a lesser area for a given velocity than when it was farther to the sun for the same given velocity. Hence, a planet travels faster when it is closer to the sun.