question_answer

A motor having an efficiency 80%, penetrates a crane having an efficiency of 40 %. What is the constant speed with which the crane lifts a body of mass 100 kg, if motor used is of 5 H.P.

Answer:

\[Usefull\,\,power=\frac{80}{100}\times \frac{40}{100}=\frac{32}{100}\,\,or\,\,32%\] \[Usefull\,\,power=\frac{5\times 32}{100}=1.6\,\,HP=1.6\times 746\,W\] \[Velocity=\frac{Power}{Force}=\frac{1.6\times 746}{100\times 9.7}=1.22\,m{{s}^{-1}}\]