We are given:
Mass of Neptune = 1.03 * 10²⁶ kg
Distance from the center of Neptune (r) = 2.27 * 10⁷
now, computing the value of the acceleration due to gravity (g)
Finding g:
We know the formula:
g = G(mass of planet) / (r)²
g = [6.67 * 10⁻¹¹ * 1.03*10²⁶] / (2.27*10⁷) [since G is 6.67*10⁻¹¹]
g = (6.87 * 10¹⁵) / (5.15 * 10¹⁴)
which can be rewritten as:
g = (6.87 * 10¹⁵ * 10⁻¹⁴) / 5.15
g = (6.87 * 10¹⁵⁻¹⁴) / 5.15
g = (6.87/5.15) * 10
g = 1.34 * 10
g = 13.4 m/s² (approx)