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QUOTE]i want to know a certain answer, i know it might 've been asked a thousand times bfore, but i wanna know if we are allowed to assume/quote the cauchy's am-gm (whatever its called) rule. u know the inequality with the arithmetic mean and geometric mean... <--- I think we cant,anyway if U...

oh no, I have no idea on this Reimann blahblah too, I think we dont need to know this in the exam,just do it like normally:)

If they ask about an investigation demonstarte a principle behind Induction Motor then either experiment on motor effect or induced emf is ok ,right??? :eek:

---> from here U can find more factors by multiply them together like 2*3 or 2*10 or 2*3*5 but there're many missing.:D The only way I can think of is fractorise it to product of prime number like 2^n*3^m*5^k.... but it take forever:D

Mechanics:D

Errr...:) Just a thought,in this case there's a change in magnetic field(switch on) thus it will produce an electric field(just like ElectroMagnetic Rad.) then this Electric field may interact with the charge in it??? Could it be???;)

Not really,back_emf in AC Motor is still due to its motion in magnetic field just as DC motor.(Consider the graph of emf produced by DC generator ,DC current varies too).Therefor,an AC sychronous motor still needs a resistor to prevent damage to it. Btw,I think only AC Induction(most AC motors...

Btw, how come all letters in the forum suddenly get too big???:confused:

OPQ is equilateral--> z2=z1*cis60 (suppose z2 is on RHS of z1)-->z2^2=z1^2* (cis60)^2=z1^2*cis120 z1*z2= (z1)^2 * cis60 z1^2 +z2^2= z1^2 +z1^2*cis120 =z1^2(1+cis120)=z1^2*cis60 ---> z1^2+z2^2= z1*z2

Hey,I'm not:( Btw ND,how come U know that???:confused:

So if they ask something like that,we should assume its the AC induction motor right???;) Btw, I've read somewhere that most AC motor are induction motor not synchronous.:)

What is a mock exam?:eek:

In the success one book,they said:"a.c motor continously produces a back_emf limits itself and so doesnt need a series resistor at start":confused: I dont get it since DC motor also has back_emf and both of them(AC+DC)spin slowly at the beginning thus small back_emf and need a resistor to...

1/85:D

Thx:D

Can some1 help me answer this plz???:confused:

93%:D -rank4:D

<--- U mean if v=0 then E=mc^2 and if v><0 (eg v=0.5c) then E=mc^2 + 1/2m (0.5c)^2 with m is relative mass ???:confused:

I just wonder that in case they ask for total energy of a moving particle such as electron: Total E= E+Ek= mc^2 +1/2 mv^2 (but do we use real mass or relative mass ?):confused:

Q52: (1+x)^n*(-x+1)^n = (1-x^2)^n consider co. of x^2r in LHS: Co.= nC2r-nC(2r-1)*nC1+...+nC(r+1)*nC(r-1)*(-1)^r-1+ nCr*nCr*(-1)^r+ nC(r-1)*nC(r+1)*(-1)^r+1+...+nC2r*(-1)^2r Now, nC2r=nC2r*(-1)^2r -nC(2r-1)*nC1= nC1*nC(2r-1)*(-1)^(2r-1) since nC(2r-1)=nC1(due to 2nd 'n 2nd last...