Kinetic energy when potential energy reduced?

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Answer

The sum of the potential and kinetic energy in any given system is always constant. If his PE = 10,000 J at the top, then the potential energy + kinetic energy must be 10,000 since at the top of the flagpole (where v = 0, kinetic energy must be zero, too.) When his potential energy is 1,000J, his kinetic energy must be 9,000 J. Hope this helps.