Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Dynamics Homework Problem.

  1. Feb 1, 2010 #1
    1. The problem statement, all variables and given/known data
    A particle P of mass m moves on a smooth, horizontal table, and is attached to a light, inextensible cord that is being pulled downward by a force F(t) as shown. The differential equations of motion are
    -T = m(r(double dot) - r*(theta(dot))^2)
    0 = r*(theta(doubledot)) + 2*r(d0t)*theta(dot)

    Let the particle be at r = r(knot) at t = 0, and let the part of the cord beneath the table be descending at constant speed vc. If the transverse component of velocity of P is r*theta(dot) = r(knot)*theta(knot)

    3. The attempt at a solution
    I realize that the problem implies that r^2*theta(dot) = a constant and since its traveling at a constant speed r(dot) = vc but I'm just confused as to what to do
    If someone can just give me an idea of where to go. A lot less concerned with getting the right answer then how.
    (just 78 not 77 in the pictures)

    Attached Files:

  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?