1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Falling chain through a hole.

  1. Jun 16, 2011 #1
    1. The problem statement, all variables and given/known data

    A flexible chain of mass M and length L lies on a frictionless table, with a very short portion of its length L0 hanging through a hole. Initially the chain is at rest. Find a general equation for y(t), the length of chain through the hole, as a function of time.
    (Hint: Use conservation of energy. The answer has the form y(t) = A eγt+ B e−γt where γ is a constant.)
    Calculate the time when 1/2 of the chain has gone through the hole.
    Data: M = 0.7 kg; L = 3.0 m; L0 = 0.5 m.

    2. Relevant equations

    E=U(y)+.5m(dy/dt)^2
    dm=M/L

    3. The attempt at a solution

    U(y)=integral of(-gydm)
    dm=M/L
    then integral of(-g(M/L)ydm)=(-Mg/(2L))(y^2)=U(y)

    then i plug into E(which is constant by conversation of energy)=U(y)+.5M(dy/dt)^2

    don't know where to go from there.
    thanks.
     
  2. jcsd
  3. Jun 16, 2011 #2
    Google "sliding chain brown university"
     
  4. Jun 16, 2011 #3
    Thank you
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook