Lucrul mecanic=forta *distanta
Lcal=240*20*10³=48*10⁵ J
Lmot=120*20*10³=24*10⁵ J
Puterea=Lucru mecanic /timp
3h si 20 min=3*60+20=200 min=60*200=12*10³ secunde
20 min=12*10² secunde
Pcal=Lcal/tcal=48*10⁵/(12*10³)=400 W
Pmot=Lmot/tmot=24*10⁵/(12*10²)=2000 W
Calul are lucru mecanic mai mare dar motoreta are putere mai mare