Escape Velocity
If a projectile is blasted from the earth, it may do one of several things. Most projectiles have a
speed such that they soon begin to curve back down towards the earththis is the parabolic flight
described by
projectile motion
. However it is possible to give a projectile sufficient speed (which
is directly proportional to its energy) such that its downward curvature is exactly matched by the
curvature of the earth. In this case, the projectile will never reach the ground, and will in fact be
in a circular orbit around the earth. If the projectile is launched with even greater energy, it will
describe an elliptical path. This is consistent with what we have just seen in
Solving the Orbits
,
where elliptical orbits were seen to have higher energies than circular ones. In fact, because
ε
=
, the greater the eccentricity of the orbit, the greater the energy. shows the differing
paths of projectiles with increasing energy.
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 Fall '10
 DavidJudd
 Physics, Energy, Mass, Projectile Motion, Light, Gravitational field, ε

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