$A$ person trying to lose weight by burning fat lifts a mass of $10 \ kg$ up to a height of $1 \ m$, $1000$ 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 $3.8 \times 10^7 \ J$ of energy per $kg$, which is converted to mechanical energy with a $20\%$ efficiency rate. Take $g = 9.8 \ m/s^2$.
- A$9.89 \times 10^{-3} \ kg$
- B$12.89 \times 10^{-3} \ kg$
- C$2.45 \times 10^{-3} \ kg$
- D$6.45 \times 10^{-3} \ kg$
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The displacement $x$ of a particle moving in one dimension under the action of a constant force is related to the time $t$ by the equation $t = \sqrt{x} + 3$,where $x$ is in meters and $t$ is in seconds. The work done by the force in the first $6$ seconds is.....$J$
DifficultIIT 1979
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DifficultTS EAMCET 2015
View SolutionAssertion $(A)$: When we bounce a ball on the ground, it comes to rest after a few bounces, losing all its energy. This is an example of violation of conservation of energy.
Reason $(R)$: Energy can change from one form to another but the total energy is always conserved.
Which of the following is true?
Reason $(R)$: Energy can change from one form to another but the total energy is always conserved.
Which of the following is true?
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