Circular motion and Gravity

Essential ideas:

• A force applied perpendicular to its displacement can result in circular motion.
• The Newtonian idea of gravitational force acting between two spherical bodies and the laws of mechanics create a model that can be used to calculate the motion of planets.

Observations and subsequent deductions led to the realization that the force must act radially inwards in all cases of circular motion.

Newton’s law of gravitation and the laws of mechanics are the foundation for deterministic classical physics. These can be used to make predictions but do not explain why the observed phenomena exist.