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 Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum Oct 22nd 2017, 09:53 AM #1 Junior Member   Join Date: Oct 2017 Posts: 8 Book friction problem Problem Suppose you are holding a heavy physics book upright between your hands as shown in the figure to the right. The mass of the book is 4.00 kg. When your right hand applies a force of 50.0 N normal to the book as shown, the book remains at rest. b.)What is the minimum possible value of the coefficient of static friction between your hands and the book? Assume the coefficient of static friction between your left hand and the book is the same as the coefficient of static friction between your right hand and the book. Known information n1=50N m=4.00kg Fnet=0 Free Body Diagram Attempt at a solution $\displaystyle x:n2-n1=0 (1)$ $\displaystyle y:Fs1+Fs1-mg=0 (2)$ $\displaystyle Fs≤µsn (3)$ $\displaystyle (1) =>n2=n1=50N$ $\displaystyle (3) =>Fs=µ(50)$ $\displaystyle (2) => 100µ=mg$ $\displaystyle (2) => µs=(4*9.80)/100$ $\displaystyle (2) => µs=.392$ The concept I'm wondering about is the minimum value of the coefficient of static friction. Was I right to set Fs=µn after I had figured out that the normal forces are the same in magnitude? If not I'm not really sure how to go about this.   Oct 22nd 2017, 11:34 AM #2 Senior Member   Join Date: Apr 2015 Location: Somerset, England Posts: 1,035 Your approach is generally correct.  Tags book, friction, problem Thread Tools Show Printable Version Email this Page Display Modes Linear Mode Switch to Hybrid Mode Switch to Threaded Mode Similar Physics Forum Discussions Thread Thread Starter Forum Replies Last Post Frostking Kinematics and Dynamics 1 Nov 7th 2010 10:13 PM jasonlewiz Kinematics and Dynamics 3 Jan 17th 2010 10:24 AM JoanF Kinematics and Dynamics 8 Dec 29th 2009 12:01 PM Solid8Snake Kinematics and Dynamics 3 Sep 22nd 2009 05:08 AM s3a Kinematics and Dynamics 1 Apr 26th 2009 08:01 PM