Help Multiple Choice. (1 Viewer)

[cook E]

Can anyone tell me how to do these questions?

The answers to question 1 is A
and question 2 is C

 

[niggas]

u suck shit

 

[cook E]

u suck shit

Nigga please...

 

[ohexploitable]

question 1

first current is flowing in such a way that it acts downwards, with gravity i.e. the combined force is 'gravity + motor effect'

F=mg+BIl
0.12=mg+5B

second current is flowing in such a way that it acts upwards, against gravity i.e. the combined force is 'gravity - motor effect'

F=mg-BIl
0.08=mg-5B

solving simultaneously

mg=0.12-5B
mg=0.08+5B

0.12-5B=0.08+5B

B=4*10^(-3)

 

[ohexploitable]

question 2

wire Y is pulled to the left by wire X,



since is just some constant for both cases, we'll just call it 'c' because i can't be bothered to type all that shit up i.e.

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wire Y is pushed to the left by wire Z, distance =2d



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[blackratpoo]

question 2

F/l= (kI1I2)/d

So you calculate individually the force btw X and Y and then individually for Y and Z. So variables we dont need are I1 and I2 as all currents are equal. We dont need K really as its a constant but keep it anyway so there is something on top. So F/l = k/d.

So for X and Y F = k/0.5 and Y and Z F= k/1. So for X and Y, resultant is 0.5F. And for Y and Z, reusltant is 1F.

Because X and Y attract and Y and Z repel you add the result. Think of where Y will move on an individual basis. When X and Y attract Y will move to the left. Likewise when Y and Z repel, Y will again move to the left. Thus both forces act on Y in the same direction.. Hence, add.

1F + 0.5F = 1.5F

Therefore C is the answer.

 

[cook E]

Thanks Guys, i'll rep you both!

 

[ohexploitable]

Rep Power: 0

lol

 

[cook E]

Rep Power: 0

lol

ye i know =[