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    Here's my working:

     80 = D \times V
     Fr = k V^2

    F=ma
    \frac{80}{V} - kV^2 = 100,000a

    \frac{80-kV^3}{100,000V} = a = v\frac{dv}{dx}

    First of all, shouldn't there be a K (constant) since it does say that resistance to motion is proportional to the square of her speed.
    I don't know how they get 8000 and how I have got an extra 0 for my 100,000. I thought that it might be something to do with me working in Ws and meant to be working in kW, but if I change it to kW, then it just becomes 0.08...which is even worse >__>

    Thanks
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    You have to find k.

    Use the fact that Vmax = 20 and equate D to Fr for that speed.
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    (Original post by steve10)
    You have to find k.

    Use the fact that Vmax = 20 and equate D to Fr for that speed.
    Thanks!
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    Is this from June 2009? It looks eerily familiar. :afraid:
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    (Original post by + polarity -)
    Is this from June 2009? It looks eerily familiar. :afraid:
    Yea I think it is
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    (Original post by + polarity -)
    Is this from June 2009? It looks eerily familiar. :afraid:
    Yep
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    I remember this question from last summer's paper :bawling:

    The method and answer seem so obvious now! However i am resitting M3 on the 29th...oh the joy!!
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    (Original post by Deepka)
    I remember this question from last summer's paper :bawling:

    The method and answer seem so obvious now! However i am resitting M3 on the 29th...oh the joy!!
    Don't worry, im sitting the same exma Good luck :P
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    (Original post by 2710)
    Yep
    :afraid: M3 ****** me over so badly. :cry:
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    (Original post by + polarity -)
    :afraid: M3 ****** me over so badly. :cry:
    Ah well, looking back at it now, we realise what big plonkers we were back there for not being able to do simple differentiation when it is disguised as Physics... Ah well, now we are a little wiser and older, we can now achieve something; the feat of not being able to do the complicated differentiation when it comes to odd looking Physics questions...
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    (Original post by 2710)
    Don't worry, im sitting the same exma Good luck :P

    Haha thanks, same to you!
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    (Original post by Mathematician!)
    Ah well, looking back at it now, we realise what big plonkers we were back there for not being able to do simple differentiation when it is disguised as Physics... Ah well, now we are a little wiser and older, we can now achieve something; the feat of not being able to do the complicated differentiation when it comes to odd looking Physics questions...
    I still don't get it. :nothing:
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    (Original post by + polarity -)
    I still don't get it. :nothing:
    Lol
    You do really. You just don't realise it yet :yep:
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    (Original post by Mathematician!)
    Lol
    You do really. You just don't realise it yet :yep:
    Nope, nada.

    I think I erased most memories of M3 after the exam violated me, like tentacles or something. :nothing:

    Spoiler:
    Show
    :beard:
    Spoiler:
    Show
    :zomg: eureka!
    Spoiler:
    Show
    You have to use F=ma, then find k!
    Spoiler:
    Show
    omdz! How did I not get this before?! :eek3:
    Spoiler:
    Show
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    (Original post by + polarity -)
    Spoiler:
    Show
    :beard:
    Spoiler:
    Show
    :zomg: eureka!
    Spoiler:
    Show
    You have to use F=ma, then find k!
    Spoiler:
    Show
    omdz! How did I not get this before?! :eek3:
    Spoiler:
    Show
    :woo:

    ...Nice.
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    How did people find the resit then? I think it was a pretty nice paper actually
 
 
 
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