An electric winch lifts a load of mass m m\,m through a vertical height h h\,h in time ttt. The potential difference across the winch motor is V V\,V and the current through it is III. If the acceleration due to gravity is ggg, what is the efficiency of the winch?
mghVIt\frac{mgh}{VIt}VItmgh
VItmgh\frac{VIt}{mgh}mghVIt
mghtVI\frac{mght}{VI}VImght
VImght\frac{VI}{mght}mghtVI
