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!

Coriolis expression - Question about sign

  1. Dec 17, 2012 #1
    1. The problem statement, all variables and given/known data

    Dear all

    I have a question concerning the Coriolis acceleration expression. I learnt it as Ac = -2ω x v, where ω is the vector which indicates the rotation axis direction of Earth and v the velocity of a body that I want to check the Coriolis effect on.

    My question: where the minus sign comes from? As far as I understand, it depends on what reference frame I use (inertial or non inertial - the minus comes from the latter, like the Earth, in my conception). Am I correct?

    Thanks in advance!

    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Dec 17, 2012 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    Welcome to PF!

    Hi Curious2013! Welcome to PF! :smile:
    There's no Coriolis force in an inertial frame. :wink:

    (same as centrifugal force)
     
  4. Dec 17, 2012 #3
    The sign is solely due to the choice of coordinates. Here's a site that derives it as positive:

    http://www.nws.noaa.gov/om/wind/deriv.shtml [Broken]
     
    Last edited by a moderator: May 6, 2017
  5. Dec 17, 2012 #4

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    no, it derives it as negative

    Coriolis force exists only in the Earth's frame (the rotating frame),

    so in that frame (d2R/dt2)Earth is on one side of the equation, and everything else on the other side …

    the Coriolis force then does have a negative sign :wink:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Coriolis expression - Question about sign
  1. Coriolis force (Replies: 29)

  2. Coriolis Force (Replies: 1)

Loading...