The gravitational force between two masses is modeled using the following function:
$F_g(r) = G \frac{m_1 m_2}{r^2}$
where $F_g$ = gravitational force (Newtons)
$G = 6.673 \times 10^{-11} \frac{Nm^2}{kg^2}$
$m_1$ = mass number 1 (kilograms)
$m_2$ = mass number 2 (kilograms)
$r$ = distance between centers of masses (meters)
Which type of mathematical model is used here to describe the gravitational force?
Linear model
Nonlinear model
Exponential model
Trigonometric model