Answer:
[tex]\large \boxed{2.04}[/tex]
Explanation:
The coefficient of friction (µ) is the ratio of the frictional force (F) to the normal force (N).
µ =F/N
1. Calculate the normal force
[tex]\begin{array}{rcl}F& = & ma\\& = & \text{20.0 kg $\times$ 9.807 m$\cdot$s}^{-2}\\& = & \text{196 N}\\\end{array}\\\text{The normal force is 196 N.}[/tex]
2. Calculate the coefficient of friction
The box is moving at a constant velocity, so the frictional force is equal and opposite to the applied force.
[tex]\begin{array}{rcl}\mu & = & \dfrac{F}{N}\\\\& = & \dfrac{\text{400 N}}{\text{196 N}}\\\\& = & \mathbf{2.04}\\\end{array}\\\text{The coefficient of friction is $\large \boxed{\mathbf{2.04}}$}[/tex]
