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 Kinematics (String attached to disk)

  1. Nov 27, 2012 #1
    1. The problem statement, all variables and given/known data
    Determine the relationship between the angular
    acceleration of the flywheel, the downward acceleration of the block, and the radius of
    the ring.

    Known data:
    Mass Ring: 1.420 kg
    Radius Ring (Inside, then Outside): 5.10 cm, 6.325 cm
    Mass Disk: 1.455 kg
    Radius Disk: 11.45 cm
    Mass Shaft: Negligable
    Radius Shaft: 0.6 cm



    2. Relevant equations

    ω=ω0 + αt
    f=ma

    3. The attempt at a solution
    I'm really lost on this, i assume that i need to calculate the tension the block places on the string (F=MA)? Could anyone give me a hint on how to get started on this.
     

    Attached Files:

  2. jcsd
  3. Nov 27, 2012 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Welcome to PF;
    Your wish is my command:
    hint: draw free-body diagrams.

    Though you could use conservation of energy and assume acceleration is constant.
     
  4. Nov 27, 2012 #3
    I understand how to do the FBD for the hanging mass. The forces acting on it are simply Fg and Ft. How would i do a FBD for the spinning mass? Would i pick a point on the outer edge to do it for?
     
  5. Nov 27, 2012 #4

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    The tension force acts at a particular location on the flywheel - creating a torque. ##\tau=I\alpha##
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook