一辆电动自行车的铭牌上给出了如下的技术参数:车型(26″电动自行车);整车质量(30kg);最大载重(12
\u4e00\u8f86\u7535\u52a8\u81ea\u884c\u8f66\u7684\u94ed\u724c\u4e0a\u7ed9\u51fa\u4e86\u5982\u4e0b\u7684\u6280\u672f\u53c2\u6570\uff1a\u8f66\u578b\uff0826\u2033\u7535\u52a8\u81ea\u884c\u8f66\uff09\uff1b\u6574\u8f66\u8d28\u91cf\uff0830kg\uff09\uff1b\u6700\u5927\u8f7d\u91cd\uff0812\uff081\uff09\u7535\u52a8\u673a\u7684\u8f93\u5165\u7684\u529f\u7387\u4e3a P \u5165 =UI\u2460 \u53c8\u7531\u4e8e P \u5165 =P \u5185 +P \u8f93\u51fa \u2461 \u7535\u52a8\u673a\u7684\u53d1\u70ed\u7684\u529f\u7387\u4e3a P \u5185 =I 2 r\u2462 \u8054\u7acb\u2460\u2461\u2462\u4ee3\u5165\u6570\u636eP \u8f93\u51fa =120W\uff0cU=40V\uff0cI=4A\uff0c \u89e3\u5f97P \u5165 =160W\uff0cr=2.5\u03a9\uff0c \uff082\uff09\u7535\u52a8\u673a\u7684\u6548\u7387\u4e3a\u03b7= p \u51fa P \u5165 \u00d7100% =75% \uff083\uff09\u82e5\u7535\u673a\u7a81\u7136\u5361\u6b7b\u65f6\uff0c\u4e3a\u7eaf\u7535\u963b\u7535\u8def\uff1aP= U 2 r = 4 0 2 2.5 =640w \u7b54\uff1a\uff081\uff09\u6b64\u8f66\u7535\u673a\u7684\u5185\u963b\u4e3a\u30002.5\u03a9\u3000\u3000\u3000\u3000\u3000\u3000\u3000\u3000\u3000\uff082\uff09\u7535\u673a\u6b63\u5e38\u5de5\u4f5c\u65f6\u7684\u6548\u7387\u4e3a75%\u3000\u3000\u3000\u3000\u3000\uff083\uff09\u5728\u989d\u5b9a\u7535\u538b\u4e0b\uff0c\u7535\u673a\u7a81\u7136\u5361\u6b7b\u65f6\uff0c\u7535\u673a\u7684\u603b\u529f\u7387\u4e3a640W
\uff081\uff09\u5728\u989d\u5b9a\u529f\u7387\u4e0b\uff0c\u5f53\u7275\u5f15\u529b\u7b49\u4e8e\u963b\u529b\u65f6\uff0c\u901f\u5ea6\u8fbe\u5230\u6700\u5927\u503c\uff0c\u6839\u636e\uff1aP=Fvm F=f=k\uff08M+m\uff09g\u5f97\uff1avm=6m/s\uff082\uff09\u8bbe\u6b64\u65f6\u52a0\u901f\u5ea6\u4e3aa\uff0c\u6839\u636eP=F1v1\u5f97\uff1aF1\uff1dPv1\uff1d1201\uff1d120N\u6839\u636e\u725b\u987f\u7b2c\u4e8c\u5b9a\u5f8b\u5f97\uff1aa=F1?k(M+m)gM+m=1m/s2\u7b54\uff1a\uff081\uff09\u4ec5\u8ba9\u7535\u673a\u5728\u989d\u5b9a\u529f\u7387\u63d0\u4f9b\u52a8\u529b\u7684\u60c5\u51b5\u4e0b\uff0c\u4eba\u9a91\u8f66\u884c\u9a76\u7684\u6700\u5927\u901f\u5ea6\u4e3a6m/s\uff1b\uff082\uff09\u4ec5\u8ba9\u7535\u673a\u5728\u989d\u5b9a\u529f\u7387\u63d0\u4f9b\u52a8\u529b\u7684\u60c5\u51b5\u4e0b\uff0c\u5f53\u8f66\u901f\u4e3av1=1.0m/s\u65f6\uff0c\u4eba\u9a91\u8f66\u7684\u52a0\u901f\u5ea6a\u7684\u5927\u5c0f\u4e3a1m/s2\uff0e
(1)电动机的输入的功率为 P入=UI ①又由于 P入=P内+P输出 ②
电动机的发热的功率为 P内=I2r ③
联立①②③代入数据P输出=120W,U=40V,I=4A,
解得P入=160W,r=2.5Ω,
(2)电动机的效率为η=
p出 |
P入 |
(3)若电机突然卡死时,为纯电阻电路:P=
U2 |
r |
402 |
2.5 |
答:(1)此车电机的内阻为 2.5Ω
(2)电机正常工作时的效率为75%
(3)在额定电压下,电机突然卡死时,电机的总功率为640W
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