A winch in a boatyard uses a 230V electric motor to raise objects from a boat onto the quay side, the winch takes 22 s to raise an object of mass 160kg through a height of 5.0m.
the motor current during this time is 14 A . Calculate the efficiency of the winch.
I know that efficiency=eng used/eng provided
eng used would be Pe=mgh =9.8*160*5=7.85*10^3 kg
I think energy provided would be electrical energy ( because that's the only other energy energy involved right)
now I know that E=0.5QV
which I thought would equal 0.5*14*22*230 (14*22 because Q=t*I)
the mark scheme however dissagrees with me removing the 0.5 from E=0.5QV