AP Physics C: Mechanics / Unit 2: Force and Translational Dynamics
2.6 Gravitational Force
Notes
$$F_g=\frac{Gm_1m_2}{r^2}$$
- Near Earth's surface, $F_g=mg$ with $g\approx9.8$ m/s².
- Doubling the distance makes the force one-fourth.
Practice
If the distance between two masses doubles, the force:
Inverse square.
The weight of a 10 kg mass on Earth:
$mg$.
An astronaut's mass on the Moon compared with Earth:
Weight changes, mass doesn't.
Gravitational potential energy for two masses far apart is:
Zero at infinity.
Ready for more? Take the Unit 2 test.