A planet moves around the sun is nearly circular orbit its period of revolution t depends upon
1)radius r of orbit.
2)mass m of the sun.
3) gravitational contact. show dimensionally t^2 proportional to

t² ∝ r³

Explanation:

Let m be the mass of the sun and m₁ be the mass of the planet and r its distance from the sun. Its gravitational force of attraction equals its centripetal force. So,

Gmm₁/r² = m₁rω² = m₁r(2π/t)²  were t is the period of orbit of the planet

Gm/r² = 4π²r/t²

rearranging we ave

t² = (4π²/Gm)r³   since k = 4π²/Gm = constant

t² = kr³ and

t² ∝ r³

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