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Kepler's third law states that square of period of revolution (T) of a planet around the sun, is proportional to third power of average distance r between sun and planet i.e. T2 = Kr3 here K is constant. If the masses of sun and planet are M and m respectively then as per Newton's
law of gravitation force of attraction between them is F = G M m here G is r2
gravitational constant. The relation between G and K is described as
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- GMK = 4π2
- K = G
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K = 1 G - GK = 4π2
Correct Option: A
As we know, orbital speed, 
| Time period T = | = | √r | ||
| vorb | √GM |
Squarring both sides,
| T2 = |  |  | 2 | = | .r3 | ||
| √GM | GM |
| ⇒ | = | = K | ||
| r3 | GM |
⇒ GMK = 4π2.
