How Far Can a Person Sit on a Table Without Tipping It Over?

[ssnapier]

Homework Statement

How Close to the edge of a 20kg table, can a 66kg person sit without tipping it over?
The table is 2.2m long and there are two legs placed 0.5 m from each end of the table with 1.2 meters between the two legs and the top of the table is 0.80 m tall

Homework Equations

I am totally at a loss here, do I use r/R=Fd/gravity?

The Attempt at a Solution

 

[davo789]

The question you need to ask is why does the table tip up at all?

 

[ssnapier]

It tips because the guy sits on the edge and disturbs the balance (changes the center of gravity). I still have no idea how what equation I should be using.

 

[davo789]

The table is symmetric, and you can assume that its mass acts from the centre of the tabletop. If you draw yourself a diagram you should see what's going on. Let me know if you don't!