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## QuestionPhysicsClass 11

A person trying to lose weight by burning fat filts a mass of $${10}{k}{g}$$ upto a being of $${1}{m}{1000}$$ 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 $${3.8}\times{10}^{{{7}}}{J}$$ of energy per kg wich is canverted to mechanical energy with $${x}{20}\%$$ efficiency rate Take $$={9.8}{m}{s}^{{-{2}}}$$
(A) $${9.89}\times{10}^{{-{3}}}{k}{g}$$
(B) $${12.89}\times{10}^{{-{3}}}{k}{g}$$
(C) $${2.45}\times{10}^{{-{3}}}{k}{g}$$
(D) $${6.45}\times{10}^{{-{3}}}{k}{g}$$

(b)$${n}=\frac{{{W}}}{{\in{p}{u}{t}}}=\frac{{{m}{g}{h}\times{1000}}}{{\in{p}{u}{t}}}=\frac{{{10}\times{9.8}\times{1}\times{1000}}}{{\in{p}{u}{t}}}$$
$$\in{p}{u}{t}=\frac{{{98000}}}{{{0.2}}}={49}\times{10}^{{{4}}}{J}$$
$${F}{a}{t}{u}{s}{e}{d}=\frac{{{49}\times{10}^{{{4}}}}}{{{3.8}\times{10}^{{{7}}}}}={12.89}\times{10}^{{-{3}}}{k}{g}$$ .