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No, back EMF is a term used to explain the opposing force or opposing change in flux created by the induced current (that creates the magnetic field)

Yes. If the conductor is not connected to an external circuit, only a potential difference (excess and deficiency of electrons on the ends), and hence an EMF will be induced within the conductor. The induced current cannot move through the conductor no there is essentially no magnetic field...

What company did your school buy their physics trials from? (just wondering what is the most popular company) or did they make them themselves?

Re: HSC 2015 2U Marathon NEXT QUESTION Find the derivative of x^3 using first principles

Re: HSC 2015 2U Marathon http://imgur.com/UhdTI5U

Re: HSC 2015 3U Marathon You could do that, but intended for you to use 3u methods It is solvable using intuition!

Re: HSC 2015 3U Marathon Next question! Express (30 x 28 x 26 x ... x 2) / (15 x 13 x 11 x ... x 1) in factorial notation (i'm running out of ideas too)

Re: HSC 2015 3U Marathon lol i) y = x^2/4a y' = x/2a f'(2ap) = p y -ap^2 = p(x-2ap) y = px -ap^2 ii) Similarly, at Q, y = qx-aq^2 -------1 px-ap^2 = qx-aq^2 x(p-q) = a(p+q)(p-q) therefore, x = a(p+q)---------2 2 -> 1 y = q(ap+aq)-aq^2 = apq Therefore, point of intersection = (a(p+q),apq)

http://imgur.com/FcHMGLH This is what it should look like Note that since (3,-27) is a minimum stat. pt., the graph must go up after that and btw, f(x) can be factorised to x^3(x-4) and the x^3 represents the triple root (pt of inflexion) at (0,0) After differentiating, (0,0) is also a stat...

I agree with this, but experimenting with different structures can really make your essay stand out

What he is asking is for the power of the leading term of the polynomial, e.g. x^2, x^3... Roots are where the curve hits the x-axis, so for my example, double root at (0,0) and single root at approx. x = 5 Single roots just cross the x-axis Double roots sort of bounce back up And triple roots...

The possibilities are virtually endless, but here's a typical example of what it might look like: http://imgur.com/gvV6rez Also note, that since (3,5) is a max sp,it is guaranteed that (0,0) is a min. Also between those two points exist a pt of inflexion (change in concavity) Other than...

Re: HSC 2015 4U Marathon No, inverse trig is 3u

Re: HSC 2015 3U Marathon http://imgur.com/XDVhTNU But still, how can you tell that it's the smallest possible number? o.o

Re: HSC 2015 3U Marathon i) i) If c is a constant then y=c represents a horizontal line. Thus,the gradient of the tangent for any point P on that line will be 0;i.e. d/dx c= 0 ii) http://imgur.com/G0HdtqQ (may or may not be right) iii) (working on it)

Too much wasted potential. The kid would be miserable every year because nothing would be challenging

Re: HSC 2015 3U Marathon I like that induction question. Couldn't get it today, i'll try it tomorrow.

Here's my go at it: http://imgur.com/rlh0DfW Not too sure (I've never heard of a double factorial until today) Step 3 might not work But basically what I did was split (2n)(2n-1)(2n-2)(2n-3)(2n-4)....3.2.1 into two components; [(2n)(2n-2)(2n-4)(2n-6)...][(2n-1)(2n-3)...] (hence isolating the...

Re: HSC 2015 4U Marathon Some insight into how you got to there? o.o

Re: HSC 2015 3U Marathon Nice first post! http://imgur.com/bNK5TeN (I think this is how you do it) Next question: Differentiate tanx using first priciples