Search Unity

Question about spheres...

Discussion in 'Physics' started by korun99, Sep 3, 2019.

  1. korun99

    korun99

    Joined:
    Sep 3, 2019
    Posts:
    2
    hello friends,im asking me long time ,when i instantiate spheres and they come over and over,why they fall not down from the side of the others under the new instantiatet? they get like a tower...but a shpere is round,so not even 1 over 1 should possible.they should fall .im sorry for my english.
    pls someone give me the answer. Zwischenablage01.jpg
     
  2. xorpheous

    xorpheous

    Joined:
    Mar 28, 2018
    Posts:
    17
    It's an unstable equilibrium for sure, but it is an equilibrium. If one sphere is offset by even a little bit, then you have an instability and the tower will collapse.The tangent plane at the top and bottom of each sphere is horizontal, therefore, there is no sideways component of the normal force to cause them to move sideways.
     
    MelvMay likes this.
  3. MelvMay

    MelvMay

    Unity Technologies

    Joined:
    May 24, 2013
    Posts:
    1,968
    It would be difficult to stack such objects in real life however it is not impossible. The fact that you would find it difficult would be due to the spheres not being uniform density or completely rigid and external factors such as not being able to place them without adding momentum to the whole stack, wind forces, ground not being exactly flat etc.

    The physics simulation tries to be perfect (within accuracy limits) so can achieve this. To be honest, it's actually pretty good that it achieves this kind of stacking which is normally hard to simulate.
     
    xorpheous likes this.
  4. hippocoder

    hippocoder

    Digital Ape Moderator

    Joined:
    Apr 11, 2010
    Posts:
    25,620
    It could be they're asleep for some reason too.