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!

Tipping a table

  1. Jan 20, 2014 #1
    This is a very well known physics problem and i already know how to solve it.

    How close to the edge of a 24kg table can a 66kg person sit without tipping it over?


    I think everybody can see the table and what's happening in there.

    MY QUESTION IS:

    Why don't we use the normal reaction due to the farther suportting?? I mean, when we calculate total torque about one supporting, we still have the other support in which there's a reaction force ating. And i think this force is as legitimate as the gravity forces of the table and person...

    I would be really glad with any answer trying to explain why is this approximation made or if I'm completely wrong in my reasoning!

    Take care!
     
  2. jcsd
  3. Jan 20, 2014 #2

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    hi ajcoelho! :smile:
    because it's zero!! :biggrin:

    so long as the total reaction force from the floor (the resultant of the reaction forces from the four legs) goes through the base of the table (the rectangle with the legs at the corners), the table will not tip

    the table will only start to tip when the resultant reaction force goes through the edge of the base

    when that happens, the individual reaction forces through the farther legs will be zero :wink:
     
  4. Jan 21, 2014 #3

    when you say edge of the base you're refering to the supporting that has become a "pivot"?
     
  5. Jan 21, 2014 #4

    tiny-tim

    User Avatar
    Science Advisor
    Homework Helper

    yes, when the reaction force reaches the edge, the tip will start about that edge as pivot :smile:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Tipping a table
  1. Tipping a block (Replies: 15)

  2. Tipping a Box (Replies: 2)

  3. Tipping a crate (Replies: 1)

Loading...