Question

A 1.83 kg book is placed on a flat desk. Suppose the coefficient of static friction between the book and the desk is 0.442 and the coefficient of kinetic friction is 0.240 . How much force is needed to begin moving the book?

Answer 1

Answer:7.92 N

Explanation:

Given

mass of book $m=1.83\ kg$

coefficient of static friction $\mu _s=0.442$

coefficient of kinetic friction $\mu _k=0.240$

To move the book, one need to overcome  the static friction  

Static friction $F_s=\mu _sN$

$F_s=\mu _s\times 1.83\times 9.8$

$F_s=0.442\times 1.83\times 9.8$

$F_s=7.92\ N$

After overcoming the Static friction , Force needed to move the block is

$F_k=\mu _kN$

$F_k=0.240\times 1.83\times 9.8$

$F_k=4.30\ N$