Gravitational Potential Energy!
The gravitational potential energy
of the earth (for example) is given by
UG(r) = - mgRe2/r,
where Re is the
earth's radius and g is the gravitational acceleration on
the surface. Notice that the potential energy is always
negative, and that it goes to zero only at an infinite
distance from the earth. On the surface of the earth it has the (negative)
value UG(Re ) = - mgRe.
The “escape speed” at any point,
near any body in space, is the speed that will result in a total
energy E = 0 for another body which is instantaneously
at that point!
Remember that we have two
conserved quantities in orbital motion: the total energy E
and the angular momentum vector L.
Center of Mass and Orbits!
Elliptical Orbits!
PLANET MEN!
DARK MATTER!
Next!!
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