问题描述：
求分析
The starting motor of a car is turning too slowly,and the mechanic has to decide whether to replace the motor,the cable,or the battery.The car's manual says that the 12V battery should have no more than 0.020Ω internal resistance,the motor no more than 0.200Ω resistance and the cable any more than 0.040Ω resistance.The mechanic turns on the motor and measures 11.4V across the battery,3.0 V across the cable,and a current of 50 A.Which part is defective?
我就想知道怎么排除是哪个出了问题～
The starting motor of a car is turning too slowly,and the mechanic has to decide whether to replace the motor,the cable,or the battery.The car's manual says that the 12V battery should have no more than 0.020Ω internal resistance,the motor no more than 0.200Ω resistance and the cable any more than 0.040Ω resistance.The mechanic turns on the motor and measures 11.4V across the battery,3.0 V across the cable,and a current of 50 A.Which part is defective?
我就想知道怎么排除是哪个出了问题～
问题解答：
我来补答
根据你给出的题目可以知道,该汽车的motor系统包括电源12V(内阻<0.02Ω),motor(内阻<0.2Ω),电缆cable(内阻=0.04Ω),motor为串联系统.根据Mechanic测量到的数据绘出下图：下面分析故障所在：1,电源内阻Rinternal=(12-11.4)V/50A=0.012Ω,满足内阻<0.02Ω,电源内阻正常；2、Motor电阻Rmotor=(11.4-3)V/50A=0.168Ω,满足motor内阻<0.2Ω,motor正常；
3、电缆cable电阻Rcable=3.0V/50A=0.06Ω,不满足cable内阻=0.04Ω,电缆故障；因此,通过以上分析,失效的部分是cable.
供你参考~~
3、电缆cable电阻Rcable=3.0V/50A=0.06Ω,不满足cable内阻=0.04Ω,电缆故障；因此,通过以上分析,失效的部分是cable.
供你参考~~ 展开全文阅读