(a) How much current flows through the motor when it is running smoothly? (b) Suddenly the string of the trimmer gets wrapped around a pole in the ground and the motor quits spinning. What is the current through the motor now? (c) How does the amount of heat dissipated in the motor during normal operation compare to the amount of heat dissipated when the motor is stuck? Calculate the ratio of the two amounts

(a) How much current flows through the motor when it is running smoothly? (b) Suddenly the string of the trimmer gets wrapped around a pole in the ground and the motor quits spinning. What is the current through the motor now? (c) How does the amount of heat dissipated in the motor during normal operation compare to the amount of heat dissipated when the motor is stuck? Calculate the ratio of the two amounts

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Question

John is using a cordless electric weed trimmer with a dc motor to cut the long weeds in his backyard. During normal operation the trimmer generates a back emf of 16 V when it is connected to an emf of 24 V dc. The total electrical resistance of the motor is 8.0 Ω.

(a) How much current flows through the motor when it is running smoothly?

(b) Suddenly the string of the trimmer gets wrapped around a pole in the ground and the motor quits spinning. What is the current through the motor now?

(c) How does the amount of heat dissipated in the motor during normal operation compare to the amount of heat dissipated when the motor is stuck? Calculate the ratio of the two amounts.

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