# Homework Help: Dynamics Homework Problem.

1. Feb 1, 2010

### RedRollins

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)

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