A person trying to lose weight (dieter )...

A person trying to lose weight (dieter ) lifts a 10 kg mass , one thousand times , to a height of 0.5 m each time .Assume that the potential energy lost each time she lowers the mass is dissipated . (a) How much work does she do against the gravitational force ? (b) Fat supplies `3.8 xx10^(7)` J of energy per kilogram which is converted to mechanical energy with a 20 % efficiency rate . How much fat will the dieter use up ?

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`= 6.45 xx 10^(-3)kg`

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