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!

Homework Help: Speed of Rotation to Experience X Acceleration

  1. Oct 31, 2007 #1
    1. The problem statement, all variables and given/known data

    How fast (in rpm) must a centrifuge rotate if a particle 9.00cm from the axis of rotation is to experience an acceleration of 115,000 g's?

    2. Relevant equations

    Either v=2(pi)r/T or v=(square root)(ar) ...not knowing which of these to use is possibly my first problem...

    3. The attempt at a solution

    First, I converted the g's to m/s^2 and got 11,734.7m/s^2 and the radius to 0.09m... I tried solving for v with both equations above and (obviously) got two completely different answers... my notes make it look like my professor was using both, but surely for different things...?

    Also, I can't seem to be able to convert this into rpm... I got the circumference to be 0.57m, so I tried to use that as one rotation, then tried using v=2(pi)r/T where T is 60s (I figured this would make it rpm)... but that gave me 0.0095m/s... which left me again with trying to figure out how to convert it into rpm... but I still don't think that's right, because the actual answer is supposed to be 3.38 x 10^4 rpm...
  2. jcsd
  3. Oct 31, 2007 #2


    User Avatar
    Homework Helper

    "v=(square root)(ar)" (you can't use the other equation because you don't know T... T is not 60)

    solve for v here... remember to convert r to m.

    then find the angular velocity. v = rw where w is angular velocity.

    then convert to rpm.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook