Question

An engine develops $10\, kW$ of power. How much time will it take to lift a mass of $200 \,kg$ to a height of $40\, m$?
(Take $g = 10\, m\, s^{-2}$)

• A. $4\,s$
• B. $5\,s$
• C. $8\,s$
• D. $10\,s$

Answer 1

Answer: (C)

$Power = \frac{\text{Work}}{\text{Time}} $
$P = \frac{mgh}{t}$ or $t= \frac{mgh}{P} $
Substituting the given values, we get
$ t=\frac{ 200\times 10\times 40}{10\times 10^{3}} = 8 \,s$