Rajasthan Police Constable Model Paper 6

Kepler’s laws of planetary motion:

• The law of Orbits/First law: Every planet moves around the sun in an elliptical orbit with the sun at one of the foci.
• The law of Area/second law: The line joining the sun to the planet sweeps out equal areas in equal interval of time i.e. areal velocity is constant.
• According to this law, the planet will move slowly when it is farthest from the sun and more rapidly when it is nearest to the sun. It is similar to the law of conservation of angular momentum.
• The law of periods/Third law: The Square of the period of revolution (T) of any planet around the sun is directly proportional to the cube of the semi-major axis of the orbit (r). Hence ${\mathit{T}}^2={\mathit{r}}^{3.}$
  Time period (T)∝ ${\mathit{r}}^{\frac{3}{2}}$

EXPLANATION:

• According to Kepler's First Law of Planetary Motion, the planets move in an elliptical orbit around the sun. So option 2 is correct.