解ï¼1ãåéè¡é©¶ï¼é度为V=S/t=120/2=60(km/h)=16.667m/sã
2ãP=FVï¼æ以F=P/V=20Ã10³/16.667=1200ï¼Nï¼ã
3ãå®å
¨çç§10kg汽油ï¼äº§ççéQ=10Ã4.6Ã10^7=4.6Ã10^8ï¼Jï¼ã
4ã汽车åå¨æºåå为W=Pt=20Ã10³Ã2Ã3600=1.44Ã10^8ï¼Jï¼ã
æ以åå¨æºæç为ï¼Î·=W/QÃ100%=1.44/4.6Ã100%=31.3%ã
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