Given:
Mass of Neptune (M₁) = 17 M₂
Here, mass of the Earth is M₂ and the distance between the Earth and the Sun is R₂. The gravitational force between the Sun and Earth (F₂) = 3.5 x 10²⁸ N
The distance between the Sun and Neptune(R₁) = 30.1 R₂
Let M be the mass of the Sun
Apply, Newton's Law of attraction
The force of attraction between the Earth and the Sun
(F₂) = G× M×M₂ / R₂² ---------------(i)
The force of attraction between the Neptune and the Sun
(F₁) = G× M×M₁ / R₁² ---------------(ii)
Now, substituting the value of M₁ and R₁ in equation (ii)
(F₁) = G× M× 17 M₂ / (30.1 R₂ )²
or, (F₁) = [17 / (30.1)²] × [G× M×M₁ / R₁²]
or, (F₁) = [17 / (30.1 )²] ×F₂
or, (F₁) = [17 / (30.1 )²] ×3.5 x 10²⁸ N
or, (F₁) = 6.6 x 10²⁶ N
Hence, the required force of attraction between the Neptune and the Sun will be 6.6 x 10²⁶ N