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Unformatted text preview: incorporated into the direction of the force in the equation above. This gives m v 2 = k e 2 / r, so the kinetic energy is KE = 1/2 k e 2 / r. The potential energy, on the other hand, is PE =  k e 2 / r. Note that the potential energy is twice as big as the kinetic energy, but negative. This relationship between the kinetic and potential energies is valid not just for electrons orbiting protons, but also in gravitational situations, such as a satellite orbiting the Earth. The total energy is: KE + PE = 1/2 ke 2 / r =  1/2 (8.99 x 10 9 )(1.60 x 1019 ) / 5.29 x 1011 This works out to 2.18 x 1018 J. This is usually stated in energy units of electron volts (eV). An eV is 1.60 x 1019 J, so dividing by this gives an energy of 13.6 eV. To remove the electron from the atom, 13.6 eV must be put in; 13.6 eV is thus the ionization energy of a groundstate electron in hydrogen....
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 Fall '10
 DavidJudd
 Physics, Energy, Orbits

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