Newton's Law of Gravity Video Lessons

Concept

# Problem: The gravitational force of a star on an orbiting planet 1 is F1. Planet 2, which is twice as massive as planet 1 and orbits at twice the distance from the star, experiences gravitational force F2.What is the ratio F2/F1? You can ignore the gravitational force between the two planets. Express your answer using two significant figures.

###### FREE Expert Solution

Force:

$\overline{){\mathbf{F}}{\mathbf{=}}\frac{\mathbf{G}\mathbf{M}\mathbf{m}}{{\mathbf{R}}^{\mathbf{2}}}}$

Taking the mass of the star to be M, the mass of the planet 1 to be m1, the mass of planet 2 to be m2, R1 be the distance between the star and planet 1, and R2 be the distance between the star and planet 2:

###### Problem Details

The gravitational force of a star on an orbiting planet 1 is F1. Planet 2, which is twice as massive as planet 1 and orbits at twice the distance from the star, experiences gravitational force F2.

What is the ratio F2/F1? You can ignore the gravitational force between the two planets. Express your answer using two significant figures.