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AQA A2 MM2B Mechanics 2 – 27th June 2016 [Exam Discussion Thread] Watch

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    (Original post by TheKian)
    Does anyone have a set formula that works for EPE questions.

    Like Final KE - Initial KE = Initial EPE - Final EPE - Work done by friction
    Well the initial energy is going to be equal to the final energy, so you just need to ensure that you include KE, GPE, EPE and any other work (e.g. Friction or other resistive forces...)

    Initial KE + Initial GPE + Initial EPE + Any other initial energy = Final KE + Final GPE + Final EPE + Any other energy used
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    (Original post by bartbarrow)
    Well the initial energy is going to be equal to the final energy, so you just need to ensure that you include KE, GPE, EPE and any other work (e.g. Friction or other resistive forces...)Initial KE + Initial GPE + Initial EPE + Any other initial energy = Final KE + Final GPE + Final EPE + Any other energy used
    Are any of them ever negative and where to the resistive forces come in?
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    Anyone else looking forward to this exam?

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    (Original post by TheKian)
    Are any of them ever negative and where to the resistive forces come in?
    Remembering some formula won't help, you should just think in terms of "all of the energy in must be equal to all of the energy out"

    The only time any of those are going to be negative is once you've rearranged them.

    If you know there is a 4000N opposing force and it's moving 10m then W=Fd, so your work done by friction is 40,000J

    So whenever you're doing a question like that, literally just sum all of the energy the particle has at the start and equate it to all of the energy it has at the end. There's nothing special to remember and the only time that will go wrong is if you forget to include a term.
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    (Original post by JPencil)
    Anyone else looking forward to this exam?

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    HELL NO, this is the final nail in the coffin
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    (Original post by TheKian)
    HELL NO, this is the final nail in the coffin
    I think a good understand of M1 and A2 Physics has really helped. I've got two more exams after M2

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    What does "Resolve Radially" mean? I keep seeing it in the mark-schemes...
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    (Original post by 2014_GCSE)
    What does "Resolve Radially" mean? I keep seeing it in the mark-schemes...
    Towards centre
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    (Original post by JPencil)
    Anyone else looking forward to this exam?

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    No cause this exam is the difference between a top rate education and working at the chippy down the road
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    (Original post by JPencil)
    I think a good understand of M1 and A2 Physics has really helped. I've got two more exams after M2

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    Same D2 and G485.. I think M2 is nice too. it's just going to be interesting to see what hard question they throw on there.
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    Just did 2015 M2. That was... different, harder than 2014 for sure. I get the feeling they're trying to introduce more questions where there are no parts, just work out the method and everything else on your own, which is nice . Last question was particularly harsh lol.
    I'd like tomorrow's paper to be similar .
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    (Original post by Jm098)
    Same D2 and G485.. I think M2 is nice too. it's just going to be interesting to see what hard question they throw on there.
    I hope Q8 (assuming we don't get 9) is an elastic one, I like those. I think D2 is going to be a killer, I still don't know some parts of the spec. What is G485? I have Phya4 (Physics)
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    (Original post by IrrationalRoot)
    Just did 2015 M2. That was... different, harder than 2014 for sure. I get the feeling they're trying to introduce more questions where there are no parts, just work out the method and everything else on your own, which is nice . Last question was particularly harsh lol.
    I'd like tomorrow's paper to be similar .
    What raw did you get on 2015? if you don't mind me asking. I'm about to do it as my offical mock, wish me luck
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    (Original post by JPencil)
    I hope Q8 (assuming we don't get 9) is an elastic one, I like those. I think D2 is going to be a killer, I still don't know some parts of the spec. What is G485? I have Phya4 (Physics)
    Yeah me too, and not like last years haha... I wouldn't have been able to do it in the time! I think D2 is just not making mistakes really and G485 is the second module in OCR Physics
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    (Original post by Jm098)
    Yeah me too, and not like last years haha... I wouldn't have been able to do it in the time! I think D2 is just not making mistakes really and G485 is the second module in OCR Physics
    I'm about to do 2015 as a mock. I'm actually looking forward to D2, from the bits I've done it seems nice. Do you know if we have to use simplex to find optimal mixed strategies?
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    (Original post by JPencil)
    What raw did you get on 2015? if you don't mind me asking. I'm about to do it as my offical mock, wish me luck
    75 . Yep you'll do well provided you understand how all the methods work.
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    (Original post by snimkar)
    Centripetal force causes the reaction to act inwards.
    Does the reaction force always act towards the centre?
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    (Original post by TheLifelessRobot)
    Does the reaction force always act towards the centre?
    Depends on the context. Is it a bead on a wire? Ball on the inside of a tube? Ball on the outside of a hemisphere? Etc etc...
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    (Original post by JC25)
    Depends on the context. Is it a bead on a wire? Ball on the inside of a tube? Ball on the outside of a hemisphere? Etc etc...
    It was a bead on a wire, check page 3 for the question.
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    Whoops, sorry I missed that.

    You don't actually know whether the reaction force acts inwards or outwards until you've done the question.

    If you think about it, the velocity may be large enough for the reaction to be acting inwards but if the velocity is small enough the reaction may be outwards. Try and imagine a bead moving very quickly and then very slowly around the wire. Just model it one way and if you end up with a negative you know it's acting in the other direction to the way you modelled it and you can just ignore the minus sign.

    (Original post by TheLifelessRobot)
    It was a bead on a wire, check page 3 for the question.
 
 
 
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