Thread: Problem starting....

A student holding a book between his hands. The forces that he exerts on the front and back covers of the book are perpendicular to the book and are horizontal. The book weights 31 N . The coefficient of the static friction between his hands and the book is .40. To keep the book from falling, what is the magnitude of the minimum pressing force that each hand must exert?

I have to draw a free body diagram to show the forces.
Arrow down for the book at W = 31N. How do I show the hands and does Fn point up??
I am totally lost on this, help please. thanks.

Originally Posted by bradycat

A student holding a book between his hands. The forces that he exerts on the front and back covers of the book are perpendicular to the book and are horizontal. The book weights 31 N . The coefficient of the static friction between his hands and the book is .40. To keep the book from falling, what is the magnitude of the minimum pressing force that each hand must exert?

I have to draw a free body diagram to show the forces.
Arrow down for the book at W = 31N. How do I show the hands and does Fn point up??
I am totally lost on this, help please. thanks.

If each hand applies a minimum force R on the book, then the maximum friction force (which acts up on the book) on each side of the book is 0.4R. You therefore require 0.8R = 31.

Having trouble understanding this, but will try to find more info on this? Thanks for the help. 39N is the answer I take it.