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Homework Help: Centripetal force help

  1. Nov 1, 2006 #1
    first off, thanks for all the help. My physics book got taken when my car got broken into and my backpack was taken. I have an old book and my pages dont coencide with my homework. everyone has been a big help. with that,, i just have two final questions about centripetal force:

    1. A ventilation fan has blades 0.25 m long rotating at 2 rad/s.
    What is the centripetal
    acceleration of a point on the outer tip of a blade?

    2. An airplane is a wide sweeping "outside" loop can create zero "g"
    (weightlessness) inside
    the aircraft cabin. What must be the radius of curvature of the
    flight path for an aircraft
    moving at 70 m/s to create a condition of "weightlessness" inside
    the aircraft?

    Im really not sure where to start with these, although I do realize that I need to account for gravity, just not sure what kind of equation im looking for.
  2. jcsd
  3. Nov 1, 2006 #2
    [tex]A_{centripital} = \frac {v^2} {r} [/tex] don't put angular velocity into that either. That should get you started atleast
  4. Nov 1, 2006 #3
    is the v^2 the velocity squared meaning the rad/s, or do i need to convert that to something else?
  5. Nov 1, 2006 #4
    rad/s is an angular velocity, you need to somehow convert that into m/s
  6. Nov 1, 2006 #5
    ok, so for 1 do i do this:

    .25m * 2 rad/s = .5

    .5^2 / .25 = 1 m/s/s

    is this correct for 1?
    Last edited: Nov 1, 2006
  7. Nov 1, 2006 #6
    and for 2:

    9.8 = 70^2 / r

    r = 500 m

    are these correct?
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