A person trying to lose weight by burning fat filts a mass of `10 kg` upto a being of `1m 1000` time . Assume that the potential energy lost each time be lower the mass is dissipated . How much far will be use up considering the work done only when the weight is lifted up ? Far supplies `3.8 xx 10^(7) J` of energy per kg wich is canverted to mechanical energy with `x 20 %` efficiency rate Take ` = 9.8 ms^(-2)`

Options

A. `9.89 xx 10^(-3) kg`
B. `12.89 xx 10^(-3) kg`
C. `2.45 xx 10^(-3) kg`
D. `6.45 xx 10^(-3) kg`

Answer

B

Explanation

(b)`n = (W)/(input) = (mgh xx 1000 )/(input) = (10 xx 9.8 xx 1 xx 1000)/(input)`
` input = (98000)/(0.2) = 49 xx 10^(4) J`
`Fat used = (49 xx 10^(4))/(3.8 xx 10^(7)) = 12.89 xx 10 ^(-3) kg` .