Statics - Impending motion, moments help

[nrp88]

Homework Statement

The cup shown in the picture is filled with 6 oz of coffee. The center of gravity is located at G. If a vertical force is applied to the rim of the cup a shown in the picture, determine its magnitude so that the cup is on the verge of tipping.

Homework Equations

sum of moments = 0
sum of forces = 0
w=mg

The Attempt at a Solution

I summed the moments around point A and came up with the force = - .5 lbs.

not sure if that's right, Do I need to factor in a normal force?

Thanks!

 

[Delphi51]

Looks good to me!

 

[nrp88]

Cool, thank you.

If you wouldn't mind, could you please take a look at my other problem posted too?

Thank you!

https://www.physicsforums.com/showthread.php?t=346855