1. The problem statement, all variables and given/known data 2. Relevant equations P=2piNT/60 P=I^2R Pin=Pout/efficieny E=P/t 3. The attempt at a solution 2.1 P=I^2R = (5)^2x48 = 1200W 2.2 Pin=Pout/efficiency = 1200/0.86 = 1395.35W 2.3 P=2piNT/60 *3100.78=2pi(500)T/60 T=0.016Nm. 2.4 Total efficiency = (45/100x86/100)x100% = 38.7% 2.5 Pin=Pout/efficiency = 1395.35/0.45 = 3100.78W* 2.6 E=P/t = 3100.78/4x60x60 = 0.215J 2.7 3.1kWx4hoursxR4.75/kWh = R58.90 I don't feel satisfied that these answers are correct, probably because they are not. The answer to 2.6 concerns me most. When can I use the equations P=I^2R and E=I^Rt?