1. Not finding help here? Sign up for a free 30min 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!

Rotational Dynamics

  1. Jan 30, 2008 #1
    1. The problem statement, all variables and given/known data
    A wheel initially rotates counterclockwise about a fixed axis, with an initial angular speed of 1.2 radians per second. If it accelerates uniformly to 2.0 radians per second clockwise during a 5 second interval, what is the magnitude of its displacement during this interval?


    2. Relevant equations
    [tex]\omega[/tex]f[tex]^{2}[/tex] - [tex]\omega[/tex]i[tex]^{2}[/tex] = 2[tex]\theta[/tex][tex]\alpha[/tex]


    3. The attempt at a solution
    [tex]\omega[/tex]i = 1.2 rad/sec
    [tex]\omega[/tex]f = 2 rad/sec
    t= 5 sec
    [tex]\theta[/tex] = ?

    2^2 - 1.2^2 = 2 [tex]\theta[/tex] ... But I found out I cant use that equation, thats where I've been stumped at...

    1. The problem statement, all variables and given/known data
    A flywheel initially spinning at 1800 rpm is brought to rest in 3 minutes. How many revolutions does the flywheel make in coming to rest?


    2. Relevant equations
    [tex]\omega[/tex]f[tex]^{2}[/tex] - [tex]\omega[/tex]i[tex]^{2}[/tex] = 2[tex]\theta[/tex][tex]\alpha[/tex]


    3. The attempt at a solution
    [tex]\omega[/tex]i = 1800 rpm
    [tex]\theta[/tex] = ?
    [tex]\omega[/tex]i = 0
    [tex]\alpha[/tex] = -3769.9 rad/min^2
    t= 3 minutes.

    0 - [(1800)(2[tex]\pi[/tex]) = 2(-3769.9)([tex]\theta[/tex]
    but i dont end up with 2700 rev....
     
    Last edited: Jan 30, 2008
  2. jcsd
  3. Jan 31, 2008 #2

    Shooting Star

    User Avatar
    Homework Helper

    Do you know any other eqn apart form this? There are three major eqns for uniform acccn, whehter linear or angular. Find alpha from one of those, and then find theta.

    omega_f = - 2 rad/s.

    Same for the other problem.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Rotational Dynamics
  1. Rotational Dynamics (Replies: 26)

  2. Rotational dynamics (Replies: 4)

  3. Rotational Dynamics (Replies: 10)

  4. Rotational dynamics (Replies: 2)

  5. Rotational Dynamics (Replies: 3)

Loading...