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Homework Help: Angular velocity and acceleration

  1. Jun 27, 2011 #1
    1. The problem statement, all variables and given/known data

    the spring oa is fixed from one end o to the bottom of a vertical circular smooth tube and from its other end to a slider a of mass m which can slide smoothly along the tube initially started from rest at a .
    find :
    i) angular velocity
    II) angular acceleration at any angle
    iii)angle at which the slider comes to instantaneous rest


    2. Relevant equations

    Conservation of energy and netwen 2nd law

    1/2 mv^2 + 1/2 Kx^2 + mgh=1/2 mv^2 + 1/2 Kx^2 + mgh

    3. The attempt at a solution

    fn=fan = mrΘdot = n-mgcosΘ +kx
    ft=f at = mrΘt double dot = -mgsinΘ

    Θ(dot)^2 = 2mgcosΘ + 2gr


    i think i made a mistake & hope someone can help with this situation
  2. jcsd
  3. Jun 29, 2011 #2


    User Avatar

    Staff: Mentor

    I'd like to see your working for your attempted solution. The fact that you have kx appearing in your expression for fn but not adding a component to ft suggests that you are viewing the spring's force as directed towards the circle's centre. It isn't.
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