1. All planets move in elliptical orbits with the sun at a focus.

2. The radius vector from the sun to the planet sweeps equal area in equal time.

3. The square of the time period of a plant is proportional to the cube of the semimajor axis of the ellipse.

(Chapter: Gravitation)

1. All planets move in elliptical orbits with the sun at a focus.

Circular path is a special case of an ellipse when the major and minor axes are equal. For a circular apth, the planet should have velocity perpendicular to the line joining it with the sun and the magnitude has to be

v = √(GM/a)

If these conditions arenot satisfied, the planet moves in an ellipse.

2. The radius vector from the sun to the planet sweeps equal area in equal time.

For a circular orbit, as the speed of the particle remains constant, it will sweep equal area in equal time.

3. The square of the time period of a plant is proportional to the cube of the semimajor axis of the ellipse.

For circular orbits this law is proved.

**Past JEE Questions**

According to Kepler’s second law, the radius vector to a plant form the sun sweeps out equal areas in equal intervals of time. This law is a consequence of the conservation of -----------------.

(JEE 1985)

Answer: Angular momentum

## No comments:

Post a Comment