Physics

• Newton's law of Universal gravitation states:

  The force of gravity between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
• The force the Earth exerts of the Moon is equal to the force the Moon exerts on the Earth.
• The apparent weight of an object changes depending on it's vertical acceleration
• F(net) = F(N) + F(weight)

  Where F(N) is the apparent weight
• The weight force due to gravity never changes (assuming no change in gravitational field)
• Whenever you are in free-fall, you experience apparent weightlessness.
• Equitorial orbits always travel above the equator

  Polar or near polar orbit over or close to the North or South pole

  Inclined orbits travel in between the equator and poles
• Equitorial orbits have high altitudes

  Polar/near polar orbits have low altitudes
• The area under a gravitational field strength-distance graph gives the energy change per kilogram of mass. To find the change in energy, the area must be multiplied by the mass, in kg, of the object
• The area under a gravitational force-distance graph gives the change in energy that an object will experience as it moves through the gravitational field