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College Physics (Urone)
Found in: Page 858

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Short Answer

Suppose you find that the belt drive connecting a powerful motor to an air conditioning unit is broken and the motor is running freely. Should you be worried that the motor is consuming a great deal of energy for no useful purpose? Explain why or why not.

The motor will utilize only enough energy to overcome friction and keep rotating if there is no load on it (which is the case with the damaged belt in issue). There's no reason to be concerned because that's not a lot of energy.

See the step by step solution

Step by Step Solution

Step 1: Definition of motor and energy

An electric motor is a machine that turns electricity into mechanical energy. The interaction between the motor's magnetic field and electric current in a wire winding generates force in the form of torque imparted to the motor's shaft in most electric motors.

Energy is the quantity that must be delivered to a body or physical system to perform work on it or heat it. Energy is a conserved quantity, meaning it can be converted in form but not created or destroyed, according to the rule of conservation of energy.

Step 2: Explanation

If the motor is running freely, that suggests it is not under any mechanical load. In this case, the motor's angular velocity is increased until the back emf is about equal to the driving emf.

The motor then turns with just enough energy to overcome friction. When compared to the energy used by an air conditioner, this energy is insignificant.


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