physics
A 72.0 kg piece of a satellite left over from an explosion with zero orbital velocity in space falls from a distance of 190 above the surface of the earth down toward earth. It arrives with 29.5 Km (M="mega") kinetic energy on earth. How many MJ energy have been lost due to friction in the earth's atmosphere ? Use the exact expression for the gravitational potential energy.
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We can calculate the gravitational potential energy of the satellite prior to its entry into the atmosphere: GPE = mgh = (72.0 kg)(9.81 m/s2)(190 km) = 12853 MJ We can calculate the kinetic energy of the satellite upon reaching the surface of the earth: KE = (1/2)(72.0 kg)(29500 m/s2)2 = 1112 MJ The energy loss due to friction in the atmosphere is equal to the difference between the two energies: Energy Loss = 12853 MJ - 1112 MJ = 11,741 MJ
