Final answer:
If the permanent magnets of a motor lose 5.0% of their strength, the torque of the motor is also expected to decrease by roughly the same percentage, which is 5.0%. Option b is the correct answer.
Step-by-step explanation:
Torque Decrease Due to Permanent Magnets Losing Strength
The torque produced by a motor depends on several factors including the strength of its permanent magnets. When assessing the percentage decrease in torque if the magnets lose a certain percentage of their strength, it is reasonable to assume, for simplicity, that the relationship between the magnetic strength and the torque is linear.
This means that if the permanent magnets in a motor lose 5.0% of their strength, the torque produced by the motor would also decrease by approximately 5.0%, assuming all other variables affecting torque remain constant. Therefore, the correct answer to the question "By how many percent is the torque of a motor decreased if its permanent magnets lose 5.0% of their strength?" is 5.0%, which corresponds to option (b).
It is important to note that in real-world scenarios, the relationship might not be strictly linear due to other factors, but for the purpose of this high school level question, linearity is an acceptable simplification.