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**Applied Maths Before/After**

12357

Comments

  • #122
    no scope codgod
    Registered Users, Registered Users 2 Posts: 64 ✭✭no scope codgod


    xJEx wrote: »
    OMG yay! But wait , somebody said last night you have to do 10 in radian mode, did you?? I cant remember what mode my calculator was in!

    And i got e = 1/16 for the last bit but then i got an increase in 1.25 cm :/

    e is the amount of speed conserved though, not the height it rises to. So in the last part if it rose to 1/16th the height, then its speed would have been 1/4 of the original speed so e would have been 1/4, not 1/16.


  • #123
    xJEx
    Registered Users, Registered Users 2 Posts: 166 ✭✭xJEx


    no scope codgod wrote: »
    e = kd (d is thickness)
    1/3 = k(2.5)
    2.5/3 = k
    k = 5/6

    1/4 = kd
    1/4 = 5d/6
    6/4 = 5d
    6 = 20d
    d = 6/20 = 3/10 = 3.33

    Is what I did

    e isnt proportional to d though, e DECRESES by a factor thats proportion to d


  • #124
    xJEx
    Registered Users, Registered Users 2 Posts: 166 ✭✭xJEx


    no scope codgod wrote: »
    e is the amount of speed conserved though, not the height it rises to. So in the last part if it rose to 1/16th the height, then its speed would have been 1/4 of the original speed so e would have been 1/4, not 1/16.

    sorry yeah i got e to be 1/4


  • #125
    xJEx
    Registered Users, Registered Users 2 Posts: 166 ✭✭xJEx


    Jackobyte wrote: »
    My differential didn't require the use of any trigonometry, only logs, so radians didn't matter. I formed a different equation than you though.

    Oh grand! I didnt know why you had to put it in radians i only used logs too! So we're right then? :D our answer?


  • #126
    Jackobyte
    Registered Users, Registered Users 2 Posts: 6,321 ✭✭✭Jackobyte


    Kingkumar wrote: »
    should it not be K(q-V) where q is the volume of tank when its full as the rate is proportional to how much water is left in the tank?
    Yeah, this was like mine. dv/dt = k(1-v) where v=water gone as a fraction of the whole container.
    no scope codgod wrote: »
    e is the amount of speed conserved though, not the height it rises to. So in the last part if it rose to 1/16th the height, then its speed would have been 1/4 of the original speed so e would have been 1/4, not 1/16.
    ****, I think you could be You are right.
    I did:
    mgh=1/2 m v^2
    Then:
    1/2 m v^2 e = mgh(1/16)
    mgh(e)=mgh(1/16)
    Therefore: e=1/16. However, that e should have been included in the v, making it (ev)^2; thus making e^2=1/16.

    Shit...


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  • #127
    xJEx
    Registered Users, Registered Users 2 Posts: 166 ✭✭xJEx


    Jackobyte wrote: »
    Yeah, this was like mine. dv/dt = k(1-v) where v=water gone as a fraction of the whole container.

    i had that but i wasnt sure how to solve it so i changed it to -dVdt = kV
    and i started with v = 1, as in none gone, and then v=1/2, as in half gone

    so like i said the rate of decrease of the volume is proportional to the fraction of the volume remaining. seeing as i had the minus sign isnt that correct? it must be if we got the same answer


  • #128
    xJEx
    Registered Users, Registered Users 2 Posts: 166 ✭✭xJEx


    can anoyne tell me what they got for end of 1, 8 or the tensions in 4?


  • #129
    Jackobyte
    Registered Users, Registered Users 2 Posts: 6,321 ✭✭✭Jackobyte


    xJEx wrote: »
    can anoyne tell me what they got for end of 1, 8 or the tensions in 4?
    Q1a: 7 seconds?
    Q8(last part): 5r/3


  • #130
    xJEx
    Registered Users, Registered Users 2 Posts: 166 ✭✭xJEx


    Jackobyte wrote: »
    Q1a: 7 seconds?
    Q8(last part): 5r/3

    That same question was on 1992 actually, the 8 so yeah thats right :)
    and yeah thats what I got in 1 too


  • #131
    xJEx
    Registered Users, Registered Users 2 Posts: 166 ✭✭xJEx


    anyobyd get 63.32N and then 71.24 N for first bitta 4?


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  • #132
    John Meighan
    Registered Users, Registered Users 2 Posts: 3 ✭John Meighan


    xJEx wrote: »
    anyobyd get 63.32N and then 71.24 N for first bitta 4?

    Yea, that's what I got, I know nobody does hydrostatics but did anyone get 400 for a?


  • #133
    xJEx
    Registered Users, Registered Users 2 Posts: 166 ✭✭xJEx


    John Meighan wrote: »
    Yea, that's what I got, I know nobody does hydrostatics but did anyone get 400 for a?

    yay i got all of 4 correct then :) sorry didnt do it.
    did you do 3 cause i got confused on it and im dying to know what the two angle answers were!


  • #134
    John Meighan
    Registered Users, Registered Users 2 Posts: 3 ✭John Meighan


    xJEx wrote: »
    yay i got all of 4 correct then :) sorry didnt do it.
    did you do 3 cause i got confused on it and im dying to know what the two angle answers were!

    I think 30 degrees for first one and 45 degrees for second one that answer could be a bit dodgy though.


  • #135
    xJEx
    Registered Users, Registered Users 2 Posts: 166 ✭✭xJEx


    John Meighan wrote: »
    I think 30 degrees for first one and 45 degrees for second one that answer could be a bit dodgy though.

    yeah i got them, but i had like 2sin(theta)cos(theta) - sin^2(theta) in the range so that had to be a max and i wasnt sure how to find the max theta so i just kinda guessed and got 5 dont know if ill get the marks for method even if my answer is right :P do they have to give u full marks if you get the answer?


  • #136
    John Meighan
    Registered Users, Registered Users 2 Posts: 3 ✭John Meighan


    xJEx wrote: »
    yeah i got them, but i had like 2sin(theta)cos(theta) - sin^2(theta) in the range so that had to be a max and i wasnt sure how to find the max theta so i just kinda guessed and got 5 dont know if ill get the marks for method even if my answer is right :P do they have to give u full marks if you get the answer?

    I changed that using formulas to sin2(theta) +.5 -Cos2(theta) and said sin max at 90 degrees and cos min at 90 degrees.


  • #137
    Jackobyte
    Registered Users, Registered Users 2 Posts: 6,321 ✭✭✭Jackobyte


    xJEx wrote: »
    yeah i got them, but i had like 2sin(theta)cos(theta) - sin^2(theta) in the range so that had to be a max and i wasnt sure how to find the max theta so i just kinda guessed and got 5 dont know if ill get the marks for method even if my answer is right :P do they have to give u full marks if you get the answer?
    I let that equal y, then differentiated and let equal 0 for max/min. Think I got 30 degrees.


  • #138
    xJEx
    Registered Users, Registered Users 2 Posts: 166 ✭✭xJEx


    John Meighan wrote: »
    I changed that using formulas to sin2(theta) +.5 -Cos2(theta) and said sin max at 90 degrees and cos min at 90 degrees.

    yeah well i knew 90 gives a max sin and a min cos so i just kind of went from there, 45 degrees gave the whole bracket bit a value of 0.5
    dammit jack may be right.. his gives 0.6 or something


  • #139
    MarieCurie22
    Registered Users, Registered Users 2 Posts: 204 ✭✭MarieCurie22


    what angle did you guys get for q2 a?


  • #140
    MarieCurie22
    Registered Users, Registered Users 2 Posts: 204 ✭✭MarieCurie22


    my answers are so f*cked up in comparison....was any body like "DISC!!!!????? WHAT!!?!?!?!??!! AGAIN!!!!?!"


  • #141
    MarieCurie22
    Registered Users, Registered Users 2 Posts: 204 ✭✭MarieCurie22


    DID YE GET 1 AND 8 **sorry cap locks** seconds for q1?


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  • #142
    Undeadfred
    Registered Users, Registered Users 2 Posts: 301 ✭✭Undeadfred


    Is there anywhere online that has the answers?


  • #143
    Monsieur Folie
    Registered Users, Registered Users 2 Posts: 1,988 ✭✭✭Monsieur Folie


    MarieCurie22 wrote: »
    DID YE GET 1 AND 8 **sorry cap locks** seconds for q1?

    I think that's what I got, interval of 7 seconds. Though I am the least trustworthy person in this thread when it comes to Applied Maths so idk. :P


  • #144
    Bionicle
    Closed Accounts Posts: 282 ✭✭Bionicle


    I've been doing some of the questions and can confirm that for q5(b), the answers are e=1/2, e=1/3, thickness is 3.75 cm and that the answers for q10 (a) is 1.5, (b) 60 m/s and 36m. I'll get crcking on more questions if you guys want. Any in particular?


  • #145
    Undeadfred
    Registered Users, Registered Users 2 Posts: 301 ✭✭Undeadfred


    Bionicle wrote: »
    I've been doing some of the questions and can confirm that for q5(b), the answers are e=1/2, e=1/3, thickness is 3.75 cm and that the answers for q10 (a) is 1.5, (b) 60 m/s and 36m. I'll get crcking on more questions if you guys want. Any in particular?

    Are you a teacher?


  • #146
    Bionicle
    Closed Accounts Posts: 282 ✭✭Bionicle


    Undeadfred wrote: »
    Are you a teacher?
    Maths college student.


  • #147
    appliedmaths
    Registered Users, Registered Users 2 Posts: 4 ✭appliedmaths


    I have put up (draft) solutions to qu1,2,3,4,5,10 on CBS Kilkenny Moodle.
    Hope they are correct! But pls feel free...!


  • #148
    ahmdoda
    Closed Accounts Posts: 185 ✭✭ahmdoda


    what did people get for question 10 part b ii?


  • #149
    xJEx
    Registered Users, Registered Users 2 Posts: 166 ✭✭xJEx


    Bionicle wrote: »
    I've been doing some of the questions and can confirm that for q5(b), the answers are e=1/2, e=1/3, thickness is 3.75 cm and that the answers for q10 (a) is 1.5, (b) 60 m/s and 36m. I'll get crcking on more questions if you guys want. Any in particular?

    **** YEAH. got all them. in your face everyone who thought it was 3.3 for the thickness! Majority does not always rule :P


  • #150
    xJEx
    Registered Users, Registered Users 2 Posts: 166 ✭✭xJEx


    Bionicle wrote: »
    I've been doing some of the questions and can confirm that for q5(b), the answers are e=1/2, e=1/3, thickness is 3.75 cm and that the answers for q10 (a) is 1.5, (b) 60 m/s and 36m. I'll get crcking on more questions if you guys want. Any in particular?

    Please do 3, 4 and the last bit of 10 :)

    oh and the value of e for 5a please :D


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  • #151
    xJEx
    Registered Users, Registered Users 2 Posts: 166 ✭✭xJEx


    appliedmaths wrote: »
    I have put up (draft) solutions to qu1,2,3,4,5,10 on CBS Kilkenny Moodle.
    Hope they are correct! But pls feel free...!

    I got the same answer for ten but when i set up my differential equation i had a minus in front of the dV/dt, is that wrong? Also, i left it as 79.32 mins, that ok do you think?


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