Question

___________velocity of the planet is constant when it revolves in an elliptical orbit around the sun.

Answer 1

1. Areal Velocity is constant: According to Kepler's second law, the line joining the sun to the planet sweeps out an equal area in an equal interval of time.

2. According to this law, the Planet moves slowly when it is at the farthest point from the sun i.e. when the planet is at aphelion the distance is maximum so the velocity is minimum.

3. Similarly, when the planet is at perihelion then the distance is minimum so velocity will be maximum. It is similar to the law of conservation of angular momentum.

Thus, the areal velocity of the planet is constant when it revolves in an elliptical orbit around the sun.