串联电阻的电压:UR=U-UL=36V-24V=12V,电路电流:I= WL UL = 40W 24V = 5 3 A;串联电阻:R= UR I = 12V 5 3 A =7.2Ω;此电阻消耗的电功率:PR=URI=12V× 5 3 A=20W;此电路工作5min消耗电能:W=UIt=36V× 5 3 A×5×60s=18000J.故答案为:7.2Ω;20W;18000J.