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!

Work in a forced oscillation

  1. Sep 9, 2009 #1
    1. The problem statement, all variables and given/known data
    How can I calculate the work which is produced by the resistance force in a forced oscillation in one period?
    The only forces on the oscillatory body are the resistance force and the external force.
    The oscillatory body is in resonance.


    2. Relevant equations
    resistance force: [tex]F_{res}=-bv[/tex] (b is the damping constant)
    external force:[tex]F_{ext}= F_{max} \cbullet \cos\omega t[/tex]
    [tex]x=Asin\omega t[/tex]
    [tex]u=u_{max}cos\omega t[/tex]


    Thanks in advance
     
  2. jcsd
  3. Sep 10, 2009 #2

    ehild

    User Avatar
    Homework Helper
    Gold Member

    How can you calculate work in general?

    ehild
     
  4. Sep 10, 2009 #3
    the work in a constant force is: W=F*d.
    Moreover the work can be calculated from the area from graph F-d.

    I can't find the work with either ways.
     
  5. Sep 10, 2009 #4
    A definition of work can be found in this http://en.wikipedia.org/wiki/Work_(physics)" [Broken].
     
    Last edited by a moderator: May 4, 2017
  6. Sep 10, 2009 #5

    ehild

    User Avatar
    Homework Helper
    Gold Member

    The work is not constant here, and the area can be calculated as integral of force with respect to the displacement.

    There is an other way to get work, by integrating power with respect to time for a given time period. And power (P) is the scalar product of force (F) and velocity (v). In case of one-dimensional motion,

    [tex]P=Fv[/tex], and work done in one period is

    [tex]
    W=\int_0^T{F(t)v(t)dt}
    [/tex]

    You know that [tex]F =-bv[/tex], and [tex]v(t)=v_{max}cos(\omega t)[/tex]. Write the product of them and integrate.

    ehild
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Work in a forced oscillation
  1. Forced oscillations (Replies: 3)

  2. FOrced Oscillations (Replies: 0)

  3. Forced Oscillations (Replies: 1)

  4. Forced oscillations (Replies: 1)

  5. Force Oscillations (Replies: 0)

Loading...