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    HSC Physics Marathon 2016

    To add to this, the reason why it is sometimes plus or minus is because the acceleration (a) is a vector. If can be either pointing downwards which is negative and why it is negative in your first example, or it can be pointing upwards which is why it is positive in your second example.
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    HSC 2016 Chemistry Marathon

    Re: HSC Chemistry Marathon 2016 Ethanol can be produced non-renewably from crude oil. Petroleum is separated into its constituent hydrocarbon molecules through a process of fractional distillation using boiling point as a difference in properties. One of the distillate fractions will contain...
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    HSC 2016 MX2 Combinatorics Marathon (archive)

    Re: HSC 2016 MX2 Combinatorics Marathon $For iv, is it P(Full House)$ =\frac{4C1\times 13C3 \times 3C1 \times 13C2}{2598960}=\frac{429}{4165}$ ?
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    Need help!! Cell potential

    I thought reduction occurred at the cathode with oxidation at the anode?
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    HSC 2016 MX1 Marathon (archive)

    Re: HSC 2016 3U Marathon This is what I think. $8 Players in each pool. Each player needs to vs all other players. First player will vs 7 other people, next will vs 6 until the last will vs 0 as that person has already vs'd everyone. The total games in each pool is $8+7+6+5+4+3+2+1 = 36$...
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    HSC 2016 Chemistry Marathon

    Re: HSC Chemistry Marathon 2016 Is this question from the production of materials module?
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    Cambridge Integration Question

    Oh that makes sense, thanks.
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    Cambridge Integration Question

    Question 14a from Cambridge 3 Unit Year 11 Exercise 11E $Sketch $y=x^2$ and mark the points A(a, $a^2$), B(-a, $a^2$), P(a, 0) and Q(-a,0).$\\$Show that $\int^a_0 x^2 \, dx = \frac{2}{3}$ (area of triangle OAP).$
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    HSC Physics Marathon 2016

    We only assume Fg=Fc if the object is in orbit. When it is on the equator of Jupiter, it will have a gravitational force and a centripetal force of different magnitudes.
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    HSC 2016 Chemistry Marathon

    Re: HSC Chemistry Marathon 2016 I'm sure that would be sufficient for 3/3. The marking guidelines from the test this question came form says 1/2 mark for naming each process, 1/2 mark for explaining each process.
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    HSC 2016 Chemistry Marathon

    Re: HSC Chemistry Marathon 2016 Fair enough, I was thinking about that in my head, just didn't explicitly mention it. Regarding LDPE/HDPE, this is what my textbook (conquering chemistry) says: In both these processes the initiator of catalyst activates an ethylene molecule by attaching to...
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    HSC 2016 Chemistry Marathon

    Re: HSC Chemistry Marathon 2016 Ethanol as a molecule has both polar and non-polar ends which allows it to dissolve polar and non-polar substances. The OH functional group on ethanol is very polar as oxygen is very electronegative. Furthermore, the hydrogen atom can from strong hydrogen bonds...
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    HSC Physics Marathon 2016

    I guess I'll provide the next question. State the period of a geostationary satellite and hence calculate the altitude of a geostationary satellite's orbit.
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    Exam Paper

    Wasn't the answer to 7 A?
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    Need help with two questions

    Yeah, sometimes deductive reasoning > inductive reasoning.
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    Need help with two questions

    But you also need to consider that the denominator in the radicand can not be equal to zero.
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    Need help with two questions

    You've only considered where the denominator is equal to zero. The expression under the square root must be also greater than or equal to zero.
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    Need help with two questions

    For (7), you should be looking at both the square root sign and the denominator. Dividing by zero is not allowed, and taking the square root of a negative number is not allowed. So let's think about the domain you can't have in this function. x can not be 2, because then the denominator is 2-2=0...
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    Perms and Combs Word

    I don't know how I would approach this question: All the letters of the word ENCUMBERANCE are arranged in a line. Find the total number of arrangements, which contain all the vowels in alphabetical order but separated by at least one consonant.
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    Complex number help!

    \frac{z_1+z_2}{z_1-z_2}\\=\frac{1+\sqrt{3}i+\sqrt{3}+i}{1+\sqrt{3}i-\sqrt{3}-i}\\=\frac{1+\sqrt{3}+(1+\sqrt{3})i}{1-\sqrt{3}+(1-\sqrt{3})I}\\=\frac{(1+\sqrt{3})(1+i)}{1-\sqrt{3})(1+i)\\=\frac{1+\sqrt{3}}{1-\sqrt{3}}\\=-2-\sqrt{3}
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