Question

A student pulls a 10 N block along a rough horizontal surface. The horizontal and the vertical components of the force that he applies are 4 N and 3 N, respectively.
What is the normal force?
If the block is in an impending motion, what is the value of the maximum static friction?
What is the coefficient of static friction?

Answer 1

There is the equilibrium in the vertical direction:

$$N+F_y-W=0$$

The normal force:

$$N=W-F_y=10-3=7 \ N$$

The value of the maximum static friction:

$$F_s=F_x=4\ N$$

The coefficient of static friction:

$$\mu_s=\frac{F_s}{N}=\frac{4}{7}=0.57$$