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** HL Physics Before / after **

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Comments

  • #452
    Kingkumar
    Registered Users, Registered Users 2 Posts: 59 ✭✭Kingkumar


    amicus wrote: »
    121 for tension ?

    i got 14N lol got that wrong anyway
    CRAP just realised i forgot to sqaure the T...14. something was sq tension :(


  • #453
    xJEx
    Registered Users Posts: 166 ✭✭xJEx


    Was the sum of the moments off by like .04 for experimental error? and for 10 was the speed of the proton 1.16x10^7? Was 12 marks just for that :/


  • #454
    amicus
    Closed Accounts Posts: 301 ✭✭amicus


    lisheen2308 wrote: »
    198N

    My friend got 120


  • #455
    amicus
    Closed Accounts Posts: 301 ✭✭amicus


    lisheen2308 wrote: »
    198N

    Did you adjust the mass or did I get it wrong?


  • #456
    Copper_pipe
    Registered Users, Registered Users 2 Posts: 11,553 ✭✭✭✭Copper_pipe


    xJEx wrote: »
    Was the sum of the moments off by like .04 for experimental error? and for 10 was the speed of the proton 1.16x10^7? Was 12 marks just for that :/

    But did you still say it verified the law of equilibrium?


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  • #457
    xJEx
    Registered Users Posts: 166 ✭✭xJEx


    Copper_pipe wrote: »
    But did you still say it verified the law of equilibrium?

    Yeah of course I'm just wondering did peope get a difference of .04 too


  • #458
    Copper_pipe
    Registered Users, Registered Users 2 Posts: 11,553 ✭✭✭✭Copper_pipe


    Ya there was a difference alright,

    Clockwise moments = 30(4) + 19.7(5.7)= 232.29

    Anti clockwise = 38.6(2) + 28.2(3) + 15.4 (4.6) = 232.64

    difference of 0.35


  • #459
    Glee_GG
    Registered Users Posts: 522 ✭✭✭Glee_GG


    Copper_pipe wrote: »
    Ya there was a difference alright,

    Clockwise moments = 30(4) + 19.7(5.7)= 232.29

    Anti clockwise = 38.6(2) + 28.2(3) + 15.4 (4.6) = 232.64

    difference of 0.35

    ^ theres also the weight of the metre stick, that was clockwise aswell


  • #460
    Leaving Cert Student
    Registered Users, Registered Users 2 Posts: 1,026 ✭✭✭Leaving Cert Student


    Glee_GG wrote: »
    ^ theres also the weight of the metre stick, that was clockwise aswell

    is that included? you sure?


  • #461
    Leaving Cert Student
    Registered Users, Registered Users 2 Posts: 1,026 ✭✭✭Leaving Cert Student


    Glee_GG wrote: »
    ^ theres also the weight of the metre stick, that was clockwise aswell

    that makes sense.. **** how many marks lost ya think that is?


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  • #462
    decisions
    Closed Accounts Posts: 8,207 ✭✭✭decisions


    Leaving Cert Student wrote: »
    is that included? you sure?

    Yep.


  • #463
    Kingkumar
    Registered Users, Registered Users 2 Posts: 59 ✭✭Kingkumar


    amicus wrote: »
    Did you adjust the mass or did I get it wrong?

    i think 198 is more right. from the formula for fundamental frequency for a stretched string. T = (F^2)(4L^2)(mew)
    Mew= 0.048/12 = 0.004, f=173 f^2=29929, L = 0.64m 4L^2 = 1.6384
    plug all of that in and u get T= 196.14 N


  • #464
    Leaving Cert Student
    Registered Users, Registered Users 2 Posts: 1,026 ✭✭✭Leaving Cert Student


    I put it in for upwards and downwards but forgot for the moments... so stupid


  • #465
    Copper_pipe
    Registered Users, Registered Users 2 Posts: 11,553 ✭✭✭✭Copper_pipe


    but if it was on the mid point would it have any affect?


  • #466
    decisions
    Closed Accounts Posts: 8,207 ✭✭✭decisions


    Did we have to do ups equal to downs?


  • #467
    Leaving Cert Student
    Registered Users, Registered Users 2 Posts: 1,026 ✭✭✭Leaving Cert Student


    Copper_pipe wrote: »
    but if it was on the mid point would it have any affect?

    it wasn't on mid point, it was on .54


  • #468
    KildareKing
    Registered Users Posts: 44 ✭KildareKing


    Leaving Cert Student wrote: »
    that makes sense.. **** how many marks lost ya think that is?

    YOU ALSO FORGOT TO COVERT cm to meters man. moments are Newtons per meter


  • #469
    Leaving Cert Student
    Registered Users, Registered Users 2 Posts: 1,026 ✭✭✭Leaving Cert Student


    KildareKing wrote: »
    YOU ALSO FORGOT TO COVERT cm to meters man. moments are Newtons per meter

    No I converted to metres


  • #470
    Kingkumar
    Registered Users, Registered Users 2 Posts: 59 ✭✭Kingkumar


    Leaving Cert Student wrote: »
    that makes sense.. **** how many marks lost ya think that is?

    ****K i didnt include that too...i assumed that as u took 50cm as the axis it would be 0... Damm thats sneaky.

    Ah well i still havent lost over 40 marks...so hopefull still an A1


  • #471
    Copper_pipe
    Registered Users, Registered Users 2 Posts: 11,553 ✭✭✭✭Copper_pipe


    http://imgur.com/Dq8V4zo

    It says about the 50 cm mark?


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  • #472
    amicus
    Closed Accounts Posts: 301 ✭✭amicus


    Kingkumar wrote: »
    i think 198 is more right. from the formula for fundamental frequency for a stretched string. T = (F^2)(4L^2)(mew)
    Mew= 0.048/12 = 0.004, f=173 f^2=29929, L = 0.64m 4L^2 = 1.6384
    plug all of that in and u get T= 196.14 N

    u forgot to multiply 0.004 by 0.64


  • #473
    Conballz
    Registered Users Posts: 22 ✭Conballz


    KildareKing wrote: »
    YOU ALSO FORGOT TO COVERT cm to meters man. moments are Newtons per meter

    It's Newton metre (N m), not per metre (N m^-1)


  • #474
    Kingkumar
    Registered Users, Registered Users 2 Posts: 59 ✭✭Kingkumar


    amicus wrote: »
    u forgot to multiply 0.004 by 0.64

    why would u do that?


  • #475
    decisions
    Closed Accounts Posts: 8,207 ✭✭✭decisions


    Shíte, I didn't realise that it was about the 50 cm mark!


  • #476
    amicus
    Closed Accounts Posts: 301 ✭✭amicus


    Kingkumar wrote: »
    why would u do that?
    because the length is o.64


  • #477
    Jackobyte
    Registered Users, Registered Users 2 Posts: 6,321 ✭✭✭Jackobyte


    Copper_pipe wrote: »
    but if it was on the mid point would it have any affect?
    Copper_pipe wrote: »
    http://imgur.com/Dq8V4zo

    It says about the 50 cm mark?

    Centre of gravity was at 50.3cm mark though (link), so the weight of the metre stick doesn't act through the midpoint. Think I got me clockwise/anticlockwise to be 2.3264 and 2.3268 N m


  • #478
    amicus
    Closed Accounts Posts: 301 ✭✭amicus


    amicus wrote: »
    because the length is o.64
    woops im wrong


  • #479
    Kingkumar
    Registered Users, Registered Users 2 Posts: 59 ✭✭Kingkumar


    amicus wrote: »
    because the length is o.64

    i dont think that matter's. if u multiply by .64 ur getting the mass of 64cm of the string. mew is mass per unit length kg/m


  • #480
    worrx
    Registered Users Posts: 22 ✭worrx


    OKKKKK Someone help me cause I am killing myself over this. For the speed of the proton in Q 10, was the answer 1.2x10^7
    or was it 2.89x10^16 ? I know the answer are extremely different BUT I got really confused and first used 1/2mv^2=qV and then cancelled that out and simply did 1/2mv^2= kinetic energy ....


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  • #481
    decisions
    Closed Accounts Posts: 8,207 ✭✭✭decisions


    worrx wrote: »
    OKKKKK Someone help me cause I am killing myself over this. For the speed of the proton in Q 10, was the answer 1.2x10^7
    or was it 2.89x10^16 ? I know the answer are extremely different BUT I got really confused and first used 1/2mv^2=qV and then cancelled that out and simply did 1/2mv^2= kinetic energy ....
    I got 2.9x10^16?


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