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!

Spinning disk

  1. Apr 4, 2009 #1
    Spinning Disk

    A disk with a diameter of 0.06 m is spinning with a constant velocity about an axle perpendicular to the disk and running through its center.

    a) How many revolutions per second would it have to rotate in order that the acceleration of the outer edge of the disk be 15 g's (i.e., 15 times the gravitational acceleration g)?

    HELP: Use the relation between the centripetal acceleration and angular velocity.
    HELP: Make sure you use the correct radius.

    b) For the frequency determined in part (a), what is the speed of a point half way between the axis of rotation and the edge of the disk?

    c) At this same frequency, what is the period of rotation of this "halfway point"?

    d) How long does it take a point on the edge of the disk to travel 1 km?

    e) Suppose we double the diameter of the disk. We still want the same 15 g acceleration at the outer edge. Let f2 be the number of revolutions per second needed to get that acceleration. What is the ratio R = f2/f, where f is your answer to part (a)? Answer according to the following key:
    1 = 0.500
    2 = 0.707
    3 = 1.000
    4 = 1.414
    5 = 2.000
    6 = none of the above

    im not sure what to do
  2. jcsd
  3. Apr 4, 2009 #2


    User Avatar
    Homework Helper

    Use the relation between the centripetal acceleration and angular velocity.
    an you find out the formula for the above?
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook