Q128 / 160 · AP EAMCET 2021 (20 Aug Shift 2) · Physics

An engine develops $20 kW$ of power. How much time will it take to lift a mass of $200 kg$ to a height of $40 m ? (g = 10 m s^{- 2})$

Solution

In physics, power is the amount of energy transferred or converted per unit time.

Power, $P = \frac{m \times g \times h}{t}$

$\Rightarrow t = \frac{m \times g \times h}{P}$

$\Rightarrow t = \frac{200 \times 10 \times 40}{20000}$

$\Rightarrow t = \frac{80000}{20000}$

$\Rightarrow t = 4 s$

Hence, the correct answer is option: 'A'.