Question: What is the gravitational force between two particles of masses m1 and m2 separated by a distance r?

Options:

1. G * (m1 * m2) / r^2
2. G * (m1 + m2) / r^2
3. G * (m1 - m2) / r^2
4. G * (m1 * m2) * r^2

Correct Answer: G * (m1 * m2) / r^2

Solution:

The gravitational force between two masses is given by Newton\'s law of gravitation, F = G * (m1 * m2) / r^2.