一辆电动自行车的铭牌上给出了如下的技术参数表
\u4e00\u8f86\u7535\u52a8\u81ea\u884c\u8f66\u7684\u94ed\u724c\u4e0a\u7ed9\u51fa\u4e86\u5982\u4e0b\u7684\u6280\u672f\u53c2\u6570\u8868\u7531\u8868\u683c\u8bfb\u51fa\u7535\u673a\u7684\u989d\u5b9a\u7535\u538bU=40V\uff0c\u989d\u5b9a\u7535\u6d41I=3.5A\uff0c\u989d\u5b9a\u8f93\u51fa\u529f\u7387P \u51fa =120W\uff0c\u5373\u4e3a\u7535\u52a8\u673a\u5728\u989d\u5b9a\u7535\u538b\u4e0b\u6b63\u5e38\u5de5\u4f5c\u65f6\u7684\u673a\u68b0\u529f\u7387\uff0c\u6240\u4ee5C\u9519\u8bef\uff1b\u7535\u673a\u6b63\u5e38\u5de5\u4f5c\u65f6\u6d88\u8017\u7684\u7535\u529f\u7387\u603b\u529f\u7387\u4e3a P \u603b =IU=40\u00d73.5W=140W\uff0c\u6240\u4ee5A\u9519\u8bef\uff0cB\u6b63\u786e\uff1b\u6545\u9009B\uff0e
\uff081\uff09\u7535\u52a8\u673a\u7684\u603b\u7684\u529f\u7387\u7684\u5927\u5c0f\u4e3aP \u603b =UI=36\u00d73.5=126W\uff0c\u7531\u56fe\u8868\u53ef\u77e5\uff0c\u7535\u52a8\u673a\u7684\u8f93\u51fa\u529f\u7387\u4e3a110W\uff0c\u6240\u4ee5\u7535\u52a8\u673a\u5728\u989d\u5b9a\u7535\u538b\u4e0b\u6b63\u5e38\u5de5\u4f5c\u7684\u6548\u7387\u4e3a \u03b7= P \u8f93\u51fa P \u603b \u00d7100%= 110 126 \u00d7100%=87%\uff1b\uff082\uff09\u5f53\u7535\u52a8\u81ea\u884c\u8f66\u7684\u7275\u5f15\u529b\u548c\u53d7\u5230\u7684\u963b\u529b\u7684\u5927\u5c0f\u76f8\u7b49\u65f6\uff0c\u7535\u52a8\u81ea\u884c\u8f66\u7684\u901f\u5ea6\u5230\u8fbe\u6700\u5927\uff0c\u7535\u52a8\u81ea\u884c\u8f66\u53d7\u5230\u7684\u963b\u529b\u7684\u5927\u5c0f\u4e3af=0.020mg=0.020\u00d7\uff0830+70\uff09\u00d710=20N\uff0c\u6240\u4ee5\u7531P=FV\u53ef\u7684\u81ea\u884c\u8f66\u7684\u6700\u5927\u7684\u901f\u5ea6\u4e3aV= P F = P f = 110 20 m/s=5.5m/s\uff0c\uff083\uff09\u7535\u52a8\u673a\u6b63\u5e38\u5de5\u4f5c\u65f6\uff0c\u635f\u5931\u7684\u529f\u7387\u4e3a126W-110W=16W\uff0c\u7535\u52a8\u673a\u7ed5\u7ebf\u7535\u963b\u53d1\u70ed\u7684\u529f\u7387\u4e3aP \u70ed =16\u00d780%=12.8W\uff0c\u6839\u636eP \u70ed =I 2 r\u53ef\u5f97\uff0c\u7535\u52a8\u673a\u7684\u7ed5\u7ebf\u7535\u963br= P \u70ed I 2 = 12.8 3\uff0e 5 2 \u03a9=1.0\u03a9\uff0e
由表格读出电机的额定电压U=40V,额定电流I=3.5A,额定输出功率P 出 =120W,即为电动机在额定电压下正常工作时的机械功率,所以C错误; 电机正常工作时消耗的电功率总功率为 P 总 =IU=40×3.5W=140W,所以A错误,B正确; 故选B. |
绛旓細鎬诲姛鐜囩瓑浜庣數鍔熺巼锛屽緱鍒帮細P鎬=IU=40脳4W=160W鐢垫満姝e父宸ヤ綔鏃剁殑鏁堢巼锛毼=P鍑篜鎬幻100%=120160脳100%=75%锛2锛夋牴鎹兘閲忓畧鎭掑緱锛屽唴閮ㄥ彂鐑姛鐜嘝鐑=P鎬-P鍑猴紝鍙圥鐑=I2r鍒欐湁P鎬-P鍑=I2rr=P鎬?
绛旓細锛1锛 锛2锛 锛3锛 璇曢鍒嗘瀽锛氾紙1锛夊洜涓 锛屾墍浠ユ湁 锛岃В寰 锛1鍒嗭級锛2锛変粠鍥句腑鍙緱 , 鏍规嵁鍏紡 锛2鍒嗭級锛3锛夊彈鍒扮殑闃诲姏锛 锛1鍒嗭級 鍙堢煡閬 褰撳叾鍖閫熻繍鍔ㄦ椂鏈夛細 鑱旂珛鍙緱锛 锛1鍒嗭級
绛旓細浠庤〃鏍兼暟鎹腑璇诲嚭棰濆畾鐢靛帇涓40V锛岄瀹氱數娴佷负3锛5A锛涙晠棰濆畾鍔熺巼涓猴細P=UI=40脳3.5=140W锛涙晠閫塀锛
绛旓細鐢辫〃鏍艰鍑虹數鏈虹殑棰濆畾鐢靛帇U=40V锛岄瀹氱數娴両=3.5A锛岄瀹氳緭鍑哄姛鐜嘝 鍑 =120W锛屽嵆涓鐢靛姩鏈哄湪棰濆畾鐢靛帇涓嬫甯稿伐浣滄椂鐨勬満姊板姛鐜囷紝鎵浠閿欒锛涚數鏈烘甯稿伐浣滄椂娑堣楃殑鐢靛姛鐜囨诲姛鐜囦负 P 鎬 =IU=40脳3.5W=140W锛屾墍浠閿欒锛孊姝g‘锛涙晠閫塀锛
绛旓細1 =120N 鏍规嵁鐗涢】绗簩瀹氬緥寰楋細a= F 1 -k(M+m)g M+m =1m/s 2 绛旓細锛1锛変粎璁╃數鏈哄湪棰濆畾鍔熺巼鎻愪緵鍔ㄥ姏鐨勬儏鍐典笅锛屼汉楠戣溅琛岄┒鐨勬渶澶ч熷害涓6m/s锛涳紙2锛変粎璁╃數鏈哄湪棰濆畾鍔熺巼鎻愪緵鍔ㄥ姏鐨勬儏鍐典笅锛屽綋杞﹂熶负v 1 =1.0m/s鏃讹紝浜洪獞杞︾殑鍔犻熷害a鐨勫ぇ灏忎负1m/s 2 锛
绛旓細搴旀湁锛歅鍑=fvm鎵浠ユ渶澶ч熷害锛歷m=P鍑篺=10020=5m/s锛3锛夎姝ゆ椂杞︾殑鍔犻熷害涓篴锛屾牴鎹墰椤跨浜屽畾寰嬶紝鏈夛細F-f=锛圡+m锛塧瑙e緱锛欶=f+锛圡+m锛塧=100Nv=PF锛100100=1m/s鏁呭姞閫熸椂闂达細t锛漹a锛10.8锛1.25s绛旓細锛1锛夋杞︽案纾佷綋鐢垫満鍦ㄩ瀹氱數鍘嬩笅姝e父宸ヤ綔鐨勬晥鐜囦负83.3%锛庯紙2锛変粎鍦ㄦ案纾佷綋鐢垫満浠...
绛旓細鐗靛紩鍔涗笌闃诲姏骞宠 锛屼负锛欶 鐗 =f=20N鏁呰緭鍑哄姛鐜囦负锛歅 鍑 =F 鐗 v=fv瑙e緱锛歷= P 鍑 f = 120 20 =6m/s绛旓細锛1锛夋杞︾殑鐢靛姩鏈哄湪棰濆畾鐢靛帇涓嬫甯稿伐浣滄椂锛屾秷鑰楃殑鐢靛姛鐜囨槸160W锛涳紙2锛夋鐢靛姩鏈虹殑鍐呴樆鏄2.5惟锛涚數鍔ㄦ満姝e父宸ヤ綔鏃剁殑鏁堢巼涓75%锛涳紙3锛夋浜洪獞杞﹁椹剁殑鏈澶...
绛旓細M+m锛塧 鈶﹁В寰梐=0.4m/s 2 鈶х瓟锛氾紙1锛鐢靛姩鑷杞︾殑鐢靛姩鏈哄湪棰濆畾鐢靛帇涓嬫甯稿伐浣滄椂鐨勬晥鐜囦负85.7%锛庯紙2锛変粎鍦ㄧ數鍔ㄦ満浠ラ瀹氬姛鐜囨彁渚涘姩鍔涚殑鎯呭喌涓嬶紝浜洪獞杞﹁椹剁殑鏈澶ч熺巼涓6.0m/s锛庯紙3锛夊綋杞﹂焩=2.0m/s鏃讹紝浜洪獞杞︾殑鍔犻熷害澶у皬涓篴=0.4m/s 2 锛
绛旓細鐢靛姩鑷杞︾殑鐢靛帇鏃40V锛岀數娴佺殑澶у皬鏄3.5A锛屾墍浠ヨ緭鍏ョ殑鍔熺巼P=UI=40脳3.5W=140W锛屾墍浠姝g‘锛庢晠閫塁锛
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