My question is a hand crank duct hoist is able to raise a 100kg fan coil unit by applying a force of 98.1N. each revolution of the crank allows 100mm raise of the load. the diameter at the crank is 381mm.calculate the efficiency of this hoist?Ideas anyone?
circumference of circle is O=2*pi*r=d*pi = 0.381m*3.14159=1.197m that is the travel hand has to make to lift something by 100m work done is W=F*y where F=ma=100kg * 9.81 m/s^2 = 981N y=0.10m (=100mm) W=981*0.1=98.1J spent energy is E=handforce*O=98.1*1.197=117.42J efficiency is n=W/E=98.1/117.42=0.835459 or 83.5459%
