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    (Original post by amanchu)
    is this a morning exam or an afternoon exam?!
    Afternoon, thankfully ;L

    OCR has the exam timetable for all exams online.
    http://www.ocr.org.uk/Images/21659-j...ertificate.pdf
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    Hey guys, check out this file, it's got like the definitions, some equations, prefixes etc you need to know (got it from my moodle) hope this helps!
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  1. File Type: doc Mechanics_definitions_2011.doc (38.5 KB, 168 views)
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    (Original post by Joseph-)
    do we have to know about 2 springs? is that in the ocr book?
    I think so ....


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    (Original post by Joseph-)
    someone post up all the units for different types of forces, e.g. young modulus, spring constants, pressure, etc...

    and all the equations we need to know!
    hope this helps
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  2. File Type: doc Mechanics_definitions_2011.doc (38.5 KB, 68 views)
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    (Original post by amanchu)
    is this a morning exam or an afternoon exam?!
    Afternoon
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    (Original post by Joseph-)
    do we have to know about 2 springs? is that in the ocr book?
    I believe you need to know the affect of the addition of springs, to each other and then parallel.

    More springs (not parallel)
    Lower K value
    Higher extension

    In Parallel
    Shared force,
    Higher K Value
    Lower Extension

    Those were my poststick notes from before the Jan exam, but now I'm questioning to whether they're correct... :confused:
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    (Original post by Liberty.)
    I believe you need to know the affect of the addition of springs, to each other and then parallel.

    More springs (not parallel)
    Lower K value
    Higher extension

    In Parallel
    Shared force,
    Higher K Value
    Lower Extension

    Those were my poststick notes from before the Jan exam, but now I'm questioning to whether they're correct... :confused:
    nothing about that in the book
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    What are the equations of power as i don't believe we're given them?
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    (Original post by rfka)
    What are the equations of power as i don't believe we're given them?
    Power is work done over time, so P = W/t
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    (Original post by rfka)
    What are the equations of power as i don't believe we're given them?
    Power = Energy / Time
    Power = Force x Velocity
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    (Original post by sohailkm96)
    Power is work done over time, so P = W/t
    Thanks - do you know if there is another equation as well? seem to recall one to do with velocity but cant remember what

    Never mind seen the other guys post
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    Can anyone define the strength of a material, for example on a stress/strain graph or force/extension graph. What would show that the material is strong?
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    For questions on moments, will we be told what points to take moments about? If not how do we know where to take the moments about? Also, does the weight of an object that acts at the centre always provide a clockwise moment?
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    (Original post by sohailkm96)
    Can anyone define the strength of a material, for example on a stress/strain graph or force/extension graph. What would show that the material is strong?
    The steepness of the gradient ?


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    (Original post by Guy96)
    The steepness of the gradient ?


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    Care to expand on that?
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    (Original post by Joseph-)
    nothing about that in the book
    With the parallel and series spring, I always explain it mathematically,

    Series: Force is the same, extension doubles (as you have twice the spring), so spring constant must be half to obey Hookes Law. ( F= (K/2)*(2E) )

    Parallel: Force is the same, extension half ( as you have they are side by side ) , so spring constant must be double obey Hookes Law. ( F=(2k)*(E/2) )

    Simplifying both variations give you F=kx.


    Hopefully that's an accepted answer, its got something along those lines in the jan 2012 markscheme.
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    (Original post by brawlerpit)
    With the parallel and series spring, I always explain it mathematically,

    Series: Force is the same, extension doubles (as you have twice the spring), so spring constant must be half to obey Hookes Law. ( F= (K/2)*(2E) )

    Parallel: Force is the same, extension half ( as you have they are side by side ) , so spring constant must be double obey Hookes Law. ( F=(2k)*(E/2) )

    Simplifying both variations give you F=kx.


    Hopefully that's an accepted answer, its got something along those lines in the jan 2012 markscheme.
    thanks
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    (Original post by blackstarz)
    For questions on moments, will we be told what points to take moments about? If not how do we know where to take the moments about? Also, does the weight of an object that acts at the centre always provide a clockwise moment?
    It always tells you where the pivot is ^_^
    And i'm not sure on the 2nd part I could do with knowing that actually :eek:
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    (Original post by chloeintheskies)
    It always tells you where the pivot is ^_^
    And i'm not sure on the 2nd part I could do with knowing that actually :eek:
    (Original post by blackstarz)
    For questions on moments, will we be told what points to take moments about? If not how do we know where to take the moments about? Also, does the weight of an object that acts at the centre always provide a clockwise moment?

    It depends, just visualise it, if the centre of gravity is on the left of the pivot, it will be anticlockwise. If it's on the right it will be clockwise. But it really depends on the question.
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    (Original post by chloeintheskies)
    It always tells you where the pivot is ^_^
    And i'm not sure on the 2nd part I could do with knowing that actually :eek:
    Yeah but i was doing some older papers where they didn't tell you the pivot where they gave you two forces and the weight and you had to determine where to take moments about to find one of the forces. So was curious as to whether we might have to do the same in these papers
 
 
 
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