In a factory it is desired to lift 2000 kg of metal through a distance of 12 m in 1 minute. Find the

Question

In a factory it is desired to lift 2000 kg of metal through a distance of 12 m in 1 minute. Find the minimum horsepower of the engine to be used.

Professor PC Thomas Classes · Answer

Calculate the work done: The work done to lift the metal is equal to its change in potential energy. 
$ \begin{aligned} & W=m g h \ & W=2000 	imes 9.8 	imes 12=235200 \mathrm{~J} \end{aligned} $
Calculate the power in Watts: Power is the rate of doing work. Time must be in seconds (1 minute = 60 s). 
$ \begin{aligned} & P=\frac{W}{t} \ & P=\frac{235200}{60}=3920 \mathrm{~W} \end{aligned} $
Convert Watts to horsepower: 
$ P_{\mathrm{hp}}=\frac{3920}{746} \approx 5.25 \mathrm{hp} $