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  1. S

    Mechanics M1: Post your doubt here

    Just one little question; have you completed the first part of the question fully? (4 (i)) Anyways, about question 4 (ii): Part 4 (i) yields two answers: Normal Component = Tcos65 + 40 Horizontal Component = Tcos25 These two answers can be obtained by using Newton's Second Law and setting...
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    Mathematics: Post your doubts here!

    It helps a load, that's an awesome diagram! Thank you so, so much! Good Luck for all your exams!
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    Mathematics: Post your doubts here!

    i) Since y = asin(bx) + c ====> we can set x = 0 to get y = c (Because asin(b * 0) = asin(0) = 0) Therefore, checking the graph when x = 0 gives us a value of 3, so c = 3. The maximum value of the sine and cosine functions for all angles is equal to 1. So taking the maximum point on the graph...
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    Mathematics: Post your doubts here!

    Guys, could someone please help out with question No. 10 (b) for the following paper? http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_w11_qp_32.pdf http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Mathematics...
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    Mathematics: Post your doubts here!

    One very important note for these kind of equation where one or more of the coefficients (a, b and c in the quadratic formula) are imaginary, (in this case the coefficient of z = (2√3)i) is that the rule of conjugate pairs being roots to the equation doesn't follow. To solve this equation, you...
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    Physics: Post your doubts here!

    Q11: Main idea here - Conservation of Momentum For this one, take the initial momentum before the collision occurs. Momentum = mv and since momentum can be positive or negative, we have to take either the right direction (positive x - axis) or the left one (negative x - axis) to be positive; in...
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    Physics: Post your doubts here!

    The potential difference between two points is defined as the amount of energy transferred per unit charge as it passes from one point to the other; This means that: V = W/Q (energy change per unit charge) and Q = It (Current x time) so V = W/It 20 = 12/15I 15I = 0.6 I = 0.04 A = Option A...
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    Physics: Post your doubts here!

    Point 1: Since the two resistors R and 2R are in parallel, they will have the same potential difference across them - therefore, V2 = V3 Point 2: The potential difference read by voltmeter V will be equal to the batteries' EMF since the battery is assumed to be ideal and thus has no internal...
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    Physics: Post your doubts here!

    Since the wave is amplitude modulated (the frequency of the carrier wave appears constant and thus unmodulated), the carrier wave's amplitude follows the envelope of the signal wave; in other words, if you connect the peaks of every wave to the next one, you should get something like a sine...
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    Mathematics: Post your doubts here!

    Okay, the first thing to notice is that they've given you the rate of change of x with respect to t in terms of x; this is not a very easy form to work with, it's like writing dy/dx in terms of y. What you can do now is take the reciprocal of each side; it is proved that dx/dy = 1/(dy/dx) so...
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    Biology paper 5 doubts

    The question says that hourly samples were made, so for each pH value, there are total 40 values taken. The number of degrees of freedom for each pH value is (n - 1), so it is totally 40 - 1 - 1 = 38 Therefore, the number of degrees of freedom is 38. Good Luck for your exams!
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    AS Physics P1 MCQs Preparation Thread.

    Any elastic material that has been stretched/deformed will want to pull the supports that are keeping it stretched in such a way as to bring it back to it's original length and/or shape. Usually, you can say that the material will pull the support/load to it's centre. Thus, there is a force on Y...
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    AS Biology P1 MCQs Preparation Thread

    Okay, Q11: First off, let's see what these substances are: Cellulose: Polymer of Beta Glucose units. Contain lots of microfibrils - long fibres made of beta glucose links linked together by beta 1-4 links. Straight chain, unlike starch. A very strong subtance when subjected to tensile forces...
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    AS Biology P1 MCQs Preparation Thread

    Q10: Amino acids have the -COOH group, which gives them acidic properties but they do not HAVE to have 2 or more -OH groups, because 2 of the 4 possible groups on the simplest possible amino acid which has 1 central carbon atom are already used used for an -NH2 group and a -COOH group. One is...
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    AS Physics P1 MCQs Preparation Thread.

    This question is tricky in that at first sight the amplitude, which is equal to the maximum displacement, may appear to be reached after 2.5 seconds, but in reality, on a displacement time graph, at the maximum displacement you can see that the gradient of the graph is zero, i.e. the velocity is...
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    AS Physics P1 MCQs Preparation Thread.

    For question 14, you need to realize that the momentum initially was equal to zero, so the momentum after the spring is released is also equal to zero. Thus: Momentum of 2 kg trolley = mv = 2 * 2 = 4 kgms^-1 and since total momentum should be zero, 4 - 1kg * v = 0, so the velocity of the 1...
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    AS Physics P1 MCQs Preparation Thread.

    First off, this is my GUESS, so it may be wrong. Anyways, here goes. Ok, so you are using a diffraction grating here, right? so the formulae used should be dsin(theta) = n*(lambda) The question asks how many images of the slit will be seen - how exactly do you see a slit? You can see the light...
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    AS Physics P1 MCQs Preparation Thread.

    Q21: If the density of a substance P is greater than the density of a substance Q, it has to have more mass per unit volume, which is where the formula for density appears. Due to this: Mass(P)/Volume(P) > Mass(Q)/Volume(Q) In this case, the number of atoms per unit volume have units of...
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    AS Physics P1 MCQs Preparation Thread.

    Ok, buddy, i'll answer these first: Q10: Since the question says the surface is smooth , no friction acts anywhere. Okay, now for this, you need to know how to draw free body diagrams. Firstly, on the block X, there are 2 forces acting, the force F that is pushing it and the Newton's Third Law...
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    AS Physics P1 MCQs Preparation Thread.

    Okay, so there are 3 springs, so the weight of the object is shared between the three; in other words, the extension force on each spring = W/3. This produces an extension of "X". Now, when the weight of 2W newtons is exerted on 2 springs (the middle one is removed) so the weight is divided into...
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