Question

A person holds a book between two of his fingers. The person is able to apply a 20 N force to either side of the pinched book. The frictional coefficient between the fingers and the book is 0.80. (a) Draw a picture with all the relevant forces (normal forces, gravity, friction). (b) What is the heaviest book the person can hold between his two fingers?

Answer 1

a)

b)

$F_{fr}=\mu N,$

$2F_{fr}=mg,\implies$

$m=\frac{2\mu N}g=3.26~N.$