contestada

A student presses a book between his hands, as the drawing indicates. The forces that he exerts on the front and back covers of the book are perpendicular to the book and are horizontal. The book weighs 40 N. The coefficient of static friction between his hands and the book is 0.37. To keep the book from falling, what is the magnitude of the minimum pressing force that each hand must exert?

Respuesta :

Answer:

[tex]54[/tex] N

Explanation:

[tex]W[/tex] = weight of the book acting downward = 40 N

[tex]f_{s}[/tex] = Static frictional force between hands and the book acting upwards

[tex]N[/tex] = Magnitude of minimum pushing force

[tex]\mu _{s}[/tex] = Coefficient of static friction = 0.37

Static frictional force between the hands and the book can be given as

[tex]f_{s} = \mu _{s} N[/tex]                              eq-1

The frictional force in upward direction balances the weight of the book is downward direction, hence

[tex]f_{s} + f_{s} = W[/tex]

[tex]2f_{s} = W[/tex]

Using eq-1

[tex]2 \mu _{s} N = W[/tex]

[tex]2 (0.37) N = 40[/tex]

[tex](0.37) N = 20[/tex]

[tex]N = 54[/tex] N

Otras preguntas