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AQA Physics PHYA4 - Thursday 11th June 2015 [Exam Discussion Thread] Watch

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    (Original post by getback339)
    Attachment 420169Is this the best way to do these kind of questions? Jan 12, question 15 multiple choice? Thanks
    That's how I do them. You can also use the fact that the ratio of the charges/masses is equal to the ratio of the distances squared, then square root (obviously negative root isn't applicable in this case), then you have a linear equation.


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    (Original post by CD223)
    That's how I do them. You can also use the fact that the ratio of the charges/masses is equal to the ratio of the distances squared, then square root (obviously negative root isn't applicable in this case), then you have a linear equation.


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    thanks!
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    (Original post by getback339)
    thanks!
    No problem!


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    Why do I not include the radius of the earth in this? I thought newtons law was the graviational force of attraction the centre of 2 masses??

    Thanks


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    (Original post by gcsestuff)
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    Why do I not include the radius of the earth in this? I thought newtons law was the graviational force of attraction the centre of 2 masses??

    Thanks


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    The orbit distance takes into account the radius.


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    Hi I don't suppose anyone knows the answer to 2 a i)

    The answers aren't in the back of the book. And this one confused me. Is it to do with electric field strength being proportional to potential difference?

    Thanks

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    (Original post by CD223)
    The orbit distance takes into account the radius.


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    So if I ever see the word orbit, that means from the centre of the earth?



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    i am had the same dream hahaha
    (Original post by gcsestuff)
    I thought this too! But surely that would be to easy for a 6 marker ??


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    (Original post by _Caz_)
    Hi I don't suppose anyone knows the answer to 2 a i)

    The answers aren't in the back of the book. And this one confused me. Is it to do with electric field strength being proportional to potential difference?

    Thanks

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    Yup! You assume it's a uniform field between the two plates.

    

E = \dfrac{V}{d}

    So increasing the potential difference means a greater E.

    As the force on the charge (treating the shuttle ball as a point charge here) is proportional to E:

    

F = EQ

    Then that means that a greater force is experienced, causing a larger change in momentum with each impact between the two walls, giving the effect that the shuttle oscillates faster


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    (Original post by gcsestuff)
    So if I ever see the word orbit, that means from the centre of the earth?



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    I would interpret that, yeah. But I've emailed my teacher to make sure - I'll let you know what he says!


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    (Original post by CD223)
    Yup! You assume it's a uniform field between the two plates.

    

E = \dfrac{V}{d}

    So increasing the potential difference means a greater E.

    As the force on the charge (treating the shuttle ball as a point charge here) is proportional to E:

    

F = EQ

    Then that means that a greater force is experienced, causing a larger change in momentum with each impact between the two walls, giving the effect that the shuttle oscillates faster


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    thank you!
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    (Original post by _Caz_)
    thank you!
    No worries


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    (Original post by CD223)
    No worries


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    Just out of curiosity, what grade are you aiming for in physics (if you don't mind me asking)?
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    (Original post by theoriginalrpr)
    i am had the same dream hahaha
    Was this about resonance?


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    (Original post by CD223)
    I would interpret that, yeah. But I've emailed my teacher to make sure - I'll let you know what he says!


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    Thanks!! You've helped me so much!! If I see a similar question I'll see what it says


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    (Original post by _Caz_)
    Just out of curiosity, what grade are you aiming for in physics (if you don't mind me asking)?
    Minimum B

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    I never knew you could do it using this method.... I always used the rms equations
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    (Original post by _Caz_)
    Just out of curiosity, what grade are you aiming for in physics (if you don't mind me asking)?
    An A hopefully! Need AAA for uni. You?


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    (Original post by gcsestuff)
    Thanks!! You've helped me so much!! If I see a similar question I'll see what it says


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    Sure! No problem.


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    (Original post by sykik)
    I never knew you could do it using this method.... I always used the rms equations
    I see! Yeah power as the rate of energy transfer is so useful!


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