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    What are the grade boundaries for Soloman L? I got 66 and I don't know what sort of UMS that would result in.
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    (Original post by Don Pedro K.)
    Pretty sure the fact that tension is the same is given by "string passes over a smooth pulley" from what I remember
    if you write both would you get the mark? do they only mark the correct work?
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    In momentum when two particles collide is the direction of motion of both of them always reversed?

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    (Original post by Clovers)
    In momentum when two particles collide is the direction of motion of both of them always reversed?

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    No, it'll usually specify in the question.
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    (Original post by amelienine)
    doesn't matter i think, but i usually leave them as i and j as the final answer
    ahh ok, it's just that I find it hard to work in the i + j form...I might just do all the working in the other form and then convert it in the end.

    Thanks
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    (Original post by Clovers)
    In momentum when two particles collide is the direction of motion of both of them always reversed?

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    no they could join together, or one could change direction
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    When doing momentum/impulse questions, if you're told the two initial speeds and one speed after the collision, does it matter whether you put v or -v for the final speed you're trying to find?




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    (Original post by Don Joiner)
    When doing momentum/impulse questions, if you're told the two initial speeds and one speed after the collision, does it matter whether you put v or -v for the final speed you're trying to find?




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    turn your speeds into velocities, then solve for V. If V is positive you will get a positive result, etc
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    (Original post by KloppOClock)
    if you write both would you get the mark? do they only mark the correct work?
    I'm not sure :s I wouldn't risk it tbh!
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    (Original post by Don Joiner)
    When doing momentum/impulse questions, if you're told the two initial speeds and one speed after the collision, does it matter whether you put v or -v for the final speed you're trying to find?




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    No, as long as you set one direction as positive then the sign of your answer will tell you what direction the particle moves after the collision. So stick with using only v, never -v.
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    So do we need to know how to use unit vectors or not?
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    How do you solve this question:
    A particle p moves with constant acceleration (-3i+j). At time t seconds, its velocity is v. When t = 0, v = 5i-3j. Find the value of t when P is moving parallel to the vector i.
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    (Original post by fpmaniac)
    How do you solve this question:
    A particle p moves with constant acceleration (-3i+j). At time t seconds, its velocity is v. When t = 0, v = 5i-3j. Find the value of t when P is moving parallel to the vector.
    parallel to which vector?
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    https://drive.google.com/file/d/0B1Z...w?pref=2&pli=1
    Question 3, if I find W first then use it to calculate R, will I still get full marks, because the mark scheme says not.
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    If I give my final answer correctly to 3 s.f. but the mark scheme only shows the answer as a fraction, will I get the answer mark? I'm really confused as they advise to give answers to 2/3 s.f.
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    (Original post by Not_a_horse)
    https://drive.google.com/file/d/0B1Z...w?pref=2&pli=1
    Question 3, if I find W first then use it to calculate R, will I still get full marks, because the mark scheme says not.
    If the mark scheme says you won't, then I'm afraid that means you won't get the marks :s! I think it is because the first part specifically states "show that blah blah blah".
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    (Original post by Kamara7)
    If I give my final answer correctly to 3 s.f. but the mark scheme only shows the answer as a fraction, will I get the answer mark? I'm really confused as they advise to give answers to 2/3 s.f.
    if it says awrt then yes, if not, probably not.

    Did you use an aproximation in your method such as g?

    also if you wrote the answer as a fraction before you rounded it they should mark it correct and ignore subsequent working i think
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    (Original post by Kamara7)
    If I give my final answer correctly to 3 s.f. but the mark scheme only shows the answer as a fraction, will I get the answer mark? I'm really confused as they advise to give answers to 2/3 s.f.
    Question paper?
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    (Original post by KloppOClock)
    parallel to which vector?
    oops. meant to say vector i.
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    (Original post by fpmaniac)
    oops. meant to say vector i.
    when its parallel to i, the sum of the J components will be 0.

    look at how you work out its current position r=r0+vt

    then set the J component of the right hand side of that equation to 0, solve for t
 
 
 
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