[答案] (1)F=G=mg=400kg×10N/kg=4000NS=2000cm²=0.2m²P= F4000NS-0.2m2 =20000pa(2)W有=Gh=4000N×10m=40000Jt= S10mV0.1m/s =100sW总=Pt=500W×100s=50000Jη= W有40000JW总50000J =80%(3)W电=Ult=220v×2.5A×60s=33000JW机械=Pt=500W×60s=30000JQ=33000J-30000J=3000...