Work, Energy & Power · JEE Main previous year questions

2016 1 question

1. Q332016 · 3 Apr 2016 · Shift 1

   A person trying to lose weight by burning fat lifts a mass of $10\mathrm{kg}$ upto a height of $1\mathrm{m}$ 1000 times. Assume that the potential energy lost each time he lowers the mass is dissipated. How much fat will he use up considering the work done only when the weight is lifted up? Fat supplies $3.8\times 10^7\mathrm{J}$ of energy per $\mathrm{kg}$ which is converted to mechanical energy with a $20\%$ efficiency rate. Take $g=9.8\mathrm{m}{\mathrm{s}}^{-2}$ :

   1. A.$9.89\times 10^{-3}\mathrm{kg}$
   2. B.$12.89\times 10^{-3}\mathrm{kg}$
   3. C.$2.45\times 10^{-3}\mathrm{kg}$
   4. D.$6.45\times 10^{-3}\mathrm{kg}$
   Show answer

   Answer: B