A planet of mass 3 × 10²⁹ gm moves around a star with a constant speed of 2 × 10⁶ ms^–1 in a circle or radius 1.5 × 10¹⁴ cm. The gravitational force exerted on the planet by the star is

8 × 10²⁶ N

Gravitational force supplies centripetal force

∴  F = $\frac{\mathrm{mv}^2}{\mathrm{r}}=\frac{3 \times 10^{29} \times\left(2 \times 10^8\right)^2}{1.5 \times 10^{14}}$ dyne

= 8 × 10³¹ dyne = 8 × 10²⁶ N