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Homework Help: Torque help

  1. Dec 7, 2003 #1
    Hello,
    Alright, this is the problem:
    Calculate the torque about the front support of a diving board exerted by a 70kg person 3.0m from that support
    here's the picture:

    ________________person
    |<-1.0m->|<--3.0m-->:

    ^ ^ ^
    | | |
    F1 F2 CG
    Alright this is what i have done so far:

    [tex]\sum T = 0 [/tex]

    [tex]\sum T = m*g*d_F1-F2 - m_p *g*d_F2-person = 0[/tex]

    [tex]\sum T = m*g* 1.0m - 70.kg * g *3.0m = 0[/tex]

    [tex] m*g*1.0m = 70.kg*g*3.0m[/tex]

    [tex] m = (70.kg*g*3.0m)/(g*1.0m)[/tex]

    [tex]m = 210kg [/tex]

    I know the answer is supposed to be 2.1 x 10^3 m*N, but i don't know what to do after finding the mass on F1; can someone help me?
     
    Last edited by a moderator: Dec 7, 2003
  2. jcsd
  3. Dec 8, 2003 #2

    ShawnD

    User Avatar
    Science Advisor

    force from gravity:
    70 * 9.81 = 686.7N

    torque:
    686.7 * 3 = 2060.1Nm
     
  4. Dec 8, 2003 #3
    ooh i see, thank you :smile:
     
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