Work, Power and EnergyMedium
Question
The power of a crane, which lifts a mass of 1000 kg to a height of 20 m in 10 s is: $\left( g = 9.8\text{ }m/s^{2} \right)$
Options
A.19.6 W
B.39.2 W
C.19.6 kW
D.39.2 kW
Solution
Sol. [Key Concept: Capacitors in parallel — common potential, energy loss] Power $= \frac{\text{~}\text{Work}\text{~}}{\text{~}\text{Time}\text{~}}$
$$\begin{matrix} & \ = \frac{mgh}{t} \\ & \ = \frac{10^{3} \times 9.8 \times 20}{10} = 19.6\text{ }kW \end{matrix}$$
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