How Long Can You Pull a Tablecloth Before a Glass Falls Off?

[physicsnoob93]

Homework Statement

If you have courage and a tight grip, you can yank a tablecloth from under the dishes on a table. What is the longest time in which the cloth can be pulled out so that a glass 6 in from the edge comes to rest before falling off the table? Assume that the coefficient of friction of the glass sliding on the tablecloth or sliding on the table top is 0.5.

Homework Equations

$$F_f=\mu mg$$

The Attempt at a Solution

Okay, so the force due to friction is $$F_f=\mu mg$$. The force will be applied for some maximum time: $$F_ft_{max}=\mu mgt_{max}$$. I'm not sure how to continue.

Thanks for your help.

 

[Doc Al]

Hint: What's the acceleration of the glass?