That gay multiple choice question (1 Viewer)

[neo_]

hey my first post!

although c and d both use eddy currents, only c affects 'mechanical" motion,like as is with the train,whereas d only affects heat.

i ended up choosing c at the end.

could someone also confirm with me what qu.2 was? i put (a 1m/s squ. thanx

 

[BillyMak]

I'd be prepared to bet money the answer was C.

Induction motors, based on eddy currents induced, conservation of momentum must apply so the motor spins. In electromagnetic braking eddy currents induced in the wheel slow it down. It uses eddy currents and conservation of momentum the same way that an induction motor does.

 

[brad_coorey]

you know wat?

i dont care... special relativity dudes, we cant travel into the past. forget it

but superman can travel into the past!

 

[vladimir]

Gotta be C

It must be C, cause the cooktop only uses eddy currents. In the motor the squirrel cage opposes the motion that created, and by the conservation law it must make it turn around

 

[Purp|e]

i had induction motor, but chg'd it to D the cooktop one. i rekon its d, so did most of the ppl at my school, but bleh ... cbf thinking about this nemore

 

[BillyMak]

it was undisputed at our school that the answer was C.

 

[Purp|e]

hmm, well im not in the mood for this but eh ... what is the conservation of energy law thingy ??? if its what i think it is, the answer is d

 

[vladimir]

conservation of energy was where the motor acted like a generator and made current whos magnetic field opposed the motion that created them. if the mag field assisted the motion, the extra motion would make stronger mag field which would make more motion.....and so forth. but that cant happen cause it would be creating energy

 

[Purp|e]

well im playing cs rite now, so im not thinking straight about physics ... but my understanding of the conservation of energy law is that energy cannot be destroyed or created, but transfered from one state to another, this enery transfer from one state to another definitely occurs in the induction cooktop... but i dont see how it occurs in the induction motor .... :\

 

[A2RAYA]

why cant it be A. DC motors dat produces back emf which slows the rotor just like the wheel being slowed down in diagram

yeh thats wat i thought...it makes sense...back emf slows down the rotation so y not A

answer me that and i'll show u a green dog

 

[SeDaTeD]

Answer is C, confirmed also by my teacher. The law of conservation of motion is applied in the same way because they both involve an induced current, which by Lenz's law, opposes the initial motion. Thus in the braking, the relative motion of train to track is reduced, and in the induction motion, the relative angular motion of the field to the squirrel cage is reduced by the rotor spinning to catch up with the field.

 

[idontgetit]

You say that both are used for motion... But the back emf in a also applies motion. Still you got a point. Here's hoping they mark both c and d right when they realise what a gay question it is

 

[utopia_parkway]

it was C. for sure. in elecromagnetic braking the eddy currents are produced to create a froce that that is in the same direction of the moving magnetic field, i.e the force acting on the rails is in the direction of motion so thus the force acting on the train is in the opposite direction of motion. the same is happening with inductio motors becuase the rotor expricnes a force that makes it want to follow the rotating magnetic field, i.e the same as the train rails having a force on them that wonts to follow the electron magent.

 

[blackbunny]

its C u sad monkeys couple of hints its C... the train is moving so does the induction motor ,,, im sure u all did this investigation on the induction motors caz when the magnetic flux changes the motor spins to opose that by lenz law (energy conservation)

what the fuck does an induction cooktop has to do with law of energy basicly its just that currents are induced in the cooktop so what if they are induced in the direction to opose that makes no difference but for induction motor it does