Newton's law
Gravity as a universal attractive force acting between all matter.
Force between point masses
![](../../graphics/equations/gravity/GravitationForce.JPG)
where G is the gravitational constant. |
Remember that gravitational force is one of the four fundamental forces.
It is only an attractive force.
Acts between masses.
Is an inverse square relationship |
Gravitational potential
Understanding of the definition of gravitational potential, including zero value at infinity, and of gravitational potential difference.
Work done in moving mass m given by![](../../graphics/equations/gravity/gravitationalPotential1.jpg)
Magnitude of V in a radial field given by:![](../../graphics/equations/gravity/gravitationalPotential2.jpg)
Graphical representations of variations of g and V with r.
V related to g by:![](../../graphics/equations/gravity/gravitationalPotential3.jpg)
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Gravitational potential is energy...
Remember that measurements are from the centres of mass - strictly speaking the masses should be point masses.
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Orbits of planets and satellites
Orbital period and speed related to radius of circular orbit.
Energy considerations for an orbiting satellite.
Significance of a geosynchronous orbit. |
You do not need Kepler's Laws - but they are good for your soul... |