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NOTES - Mechanics

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  • 7/31/2019 NOTES - Mechanics

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    F = ma

    F12

    F21

    F21 = F12

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    F = 0

    Fx = 0

    Fy = T Fg = 0 T = Fg

    Fy = n Fg = 0 n = Fg

    Fy = T = max ax =

    T

    m

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    Fy = mg R

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    x = g kv2v2

    mx = mg mkv2 x = g kv2

    v dvdx

    = g kv2v

    gkv2dv =

    dx

    12k ln(g kv2) = x + C,

    v2 = gk

    (1 e2kx)

    v =

    gk

    (1 e2kh)

    v2 = U2 2gR2( 1R 1

    x)

    9.8ms2

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    a =dv

    dt= k

    x2

    g = kR2 k = gR2

    dv

    dt

    =

    gR2

    x2

    vdv

    dx= gR

    2

    x2

    vdv = gR

    2

    x2dx

    v2

    2= gR2

    1

    x

    + C

    U2

    2= gR2( 1

    R) + C C = U

    2

    2+ gR

    v2 = U2 2gR2( 1R 1

    x)

    U2 = 2gR2(1

    R 1

    x)

    x =2gR2

    2gR

    U2

    x

    2gR U2 0

    U =

    2gR 11.2kms1

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    a = k(1

    v2), k > 0

    v210 ms2U ms1

    v =10U

    10+Ut ms1x = 10ln(1 + Ut10 ) m

    v + v3

    x = arctan( Qv1+Qv )

    t = 12 ln(Q2(1+v2)v2(1+Q2) v

    2

    t

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    Fx = Fcos

    Fy = Fsin

    = ddt

    v = r at = ddt =

    dd

    12

    2 = dd

    =

    ac = r2 = v2

    r

    Fc = m v2

    r = mr T = 2

    T = mv2

    r= (3)(

    16

    2) = 8 N

    mv2

    r= 147 v =

    147

    r

    m= 7

    2

    v = r = 7

    2 = 722

    rad/s

    =7

    2

    4rev/s

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    P F = 0

    mg N =mv2

    r

    N = mg mv2

    r= 3400 N

    mg =mv2

    r v2 = gr

    ms2

    F = kmM

    r2

    mg = kmM

    R2 k = gR

    2

    M

    F =mgR2

    r2= mr2

    =2

    T 7.3 105 rad/s

    r3 =gR2

    2=

    (9.8)(6.4 106)2(7.3 105)2 = 7.53 10

    22 r = 4.22 107 m

    v = r = (4.22 107)(7.3 105) = 3000 ms1

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    Horizontally : Tsin = mr2

    V ertically : Tcos = mg

    l2 = r2 + h2

    r = lsinh = lcos

    T = ml2 tam = r2

    g= v

    2

    gr

    tan = rh

    =

    gh

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    F + mgsin =mv2

    rcos

    Nmgcos = mv2

    rsin

    mv2

    r= Fcos + Nsin

    mg = Ncos Fsin

    F = 0

    tan =v2

    gr

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    F + mgsin =

    mv2

    r cos

    tan =v2

    gr=

    13.42

    (9.8)(50) = 20.1

    T = 2

    hg

    40


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