Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Center of mass

  1. Jan 10, 2015 #1
    Is center of mass a vector quantity. If so then how? Is it directed towards Earth's center?
     
  2. jcsd
  3. Jan 10, 2015 #2

    Andrew Mason

    User Avatar
    Science Advisor
    Homework Helper

    The centre of mass is a point. As such, it is expressed as a displacement vector from the origin of the reference frame that is being used. If it coincides with the origin, it is the vector (0, 0, 0).

    AM
     
  4. Jan 10, 2015 #3
    Thanks a lot.
     
  5. Jan 10, 2015 #4

    Dale

    Staff: Mentor

    The center of mass is a position. Technically position is an affine space, not a vector space. At least in non relativistic physics.
     
  6. Jan 10, 2015 #5

    Andrew Mason

    User Avatar
    Science Advisor
    Homework Helper

    Shayan,

    Just to follow up on this, the centre of mass of a mass distribution is conveniently expressed as the sum of each of the point masses in the system multiplied by their displacement vector from the origin divided by the total mass:

    [tex]\vec{R} =\frac{1}{\sum_{i}m_i} \sum_{i} m_i\vec{r}_i[/tex]

    See, for example, Barger & Olson, Classical Mechanics, A Modern Perspective, first ed., ch. 5-1, p. 156-160

    AM
     
    Last edited: Jan 10, 2015
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Center of mass
  1. Center of mass? (Replies: 3)

  2. Center of mass (Replies: 2)

Loading...