The kinetic frictional force:

$\overline{){{\mathbf{F}}}_{{\mathbf{f}}}{\mathbf{=}}{{\mathbf{\mu}}}_{{\mathbf{k}}}{\mathbf{N}}}$

The normal force:

$\overline{){\mathbf{N}}{\mathbf{=}}{\mathbf{m}}{\mathbf{g}}}$

**a)**

The sum of horizontal forces on A is:

ΣF_{A} = T - f_{A}

0 = T - μ_{k}m_{A}g

The sum of horizontal forces acting on B:

ΣF_{B} = W_{B} - T

0 = W_{B} - T = m_{B}g - T

Consider the system shown in the figure (Figure 1). Block A weighs 46.9 N and block B weighs 30.1 N.Once block B is set into downward motion, it descends at a constant speed.

a.) Calculate the coefficient of kinetic friction between block *A* and the tabletop.

b.) A cat, also of weight 46.9 N, falls asleep on top of block *A*. If block *B* is now set into downward motion, what is its acceleration magnitude?

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