Physics, 08.10.2019 14:00, emilymariec4036

What is the difference between an induced and a permanent magnet?

Answers: 2

Show answers

Answers

INDUCTION MOTOR:-

Speed:-Less speed range than PMAC motors • Speed range is a function of the drive being used — to 1,000:1 with an encoder, 120:1 under field-oriented control

Reliability:-Waste heat is capable of degrading insulation essential to motor operation • Years of service common with proper operation

Power density:-Induction produced by squirrel cage rotor inherently limits power density

Accuracy:-Flux vector and field-oriented control allows for some of accuracy of servos

Cost:-Relatively modest initial cost; higher operating costs

PERMANENT MAGNET MORTOR:-

speed:-VFD-driven PMAC motors can be used in nearly all induction-motor and some servo applications • Typical servomotor application speed — to 10,000 rpm — is out of PMAC motor range

Reliability:-Lower operating temperatures reduces wear and tear, maintenance • Extends bearing and insulation life • Robust construction for years of trouble-free operation in harsh environments.

power density:-Rare-earth permanent magnets produce more flux (and resultant torque) for their physical size than induction types.

Accuracy:-Without feedback, can be difficult to locate and position to the pinpoint accuracy of servomotors

Cost:-Exhibit higher efficiency, so their energy use is smaller and full return on their initial purchase cost is realized more quickly

answered: Guest

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.

answered: Guest

The answer is frictional force

Other questions on the subject: Physics

Physics, 21.06.2019 17:00, jordynsmith02

Shelly experiences a backward jolt when the driver starts the school bus. which of the following explains this phenomenon? a. the inertia of shelly b. the inertia of the bus c. the normal force of the seats on shelly d. the net force acting on shelly in a backward direction e. a zero net force acting on shelly

Answers: 1

continue

Physics, 22.06.2019 01:30, markmeinberg

Ajet plane has a sound level of 120 db at a distance of 60 m. what is the q23. sound level at a distance of 6.0 km? (60)2 (6000)? om solution 80db db, hint: 16x assume ultrasound waves travel through the body of an animal at 1540 q24. m/s. if a 30,000 hz signal were reflected off a portion of a heart which was moving toward the source at 3 m/s, what frequency signal would return to the stationary source? solution 30.117hz

Answers: 3

continue

Physics, 22.06.2019 05:10, lololololol12555

What do elements in a family tend to share. a.) similar periods b.) similar groups c.) similar atomic symbols d.) similar chemical properties and characteristics

Answers: 2

continue

Physics, 22.06.2019 12:30, clmorcutt420

Apositive charge moves in the direction of an electric field. which of the following statements are true? check all that apply. check all that apply. 1.the potential energy associated with the charge decreases. 2. the electric field does positive work on the charge. 3. the electric field does negative work on the charge. 4. the potential energy associated with the charge increases. 5. the electric field does not do any work on the charge. 6. the amount of work done on the charge cannot be determined without additional information.