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Newtons Law of Motion/Free Falling objct

  1. Sep 28, 2006 #1
    Hi I have a problem I need someone to check over and see if I have it right!

    Thank you for trying in advance

    Responding to an alarm, a 92kg fireman slides down a pole to the ground floor, 3.2m below. The fireman starts at rest and lands with a speed of 4.9 m/s. Find the average force exerted on the fireman by the pole.

    m=92 Kg, d=3.2m, Vf= 4m/s
    I found time first: (Can I do that?)
    y-vector
    y=0.5 (Voy+Vy)t
    3.2m =0.5 (0+4m/s)t
    t=1.6s

    y=yo+Voyt+0.5ayt^2
    ay=2(y-yo) / t^2
    ay = (2)(0-3.2m) / 1.6s
    ay=-4m/s^2

    Sum of Fy= F-mg
    F-mg=ma
    F= may+mg = m(ay+g)
    F = (92kg)(-4m/s^2+9.81m/s^2)
    F= 534.5N
    Thanks
     
  2. jcsd
  3. Sep 28, 2006 #2
    Compare the quantities given in the problem to the quantities inserted into the formulas. And watch for exponents.
     
  4. Sep 28, 2006 #3
    thanks

    I think how I solved the above question is wrong because I found time and then solved for accerlation instead of just finding accerlation from the information given and then account for all the forces...

    And for the free falling object I forgot what I was going to ask....
     
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