Question

the coefficients of static and kinetic friction between the paper used in a cardboard box and a particular wooden floor are 0.5 and 0.3, respectively. calculate the force that must be applied to slide a box with a weight of 40 n over the floor at a constant speed. (1 point)

32 n
40 n
20 n
12 n

Explanation:

Step1: Identify normal force

The normal force $N$ equals the weight of the box since the box is on a horizontal surface. So $N = 40\ N$.

Step2: Determine friction - force formula

When the box is moving at a constant speed, the applied force $F$ equals the kinetic - friction force. The formula for kinetic - friction force is $F_f=\mu_kN$, where $\mu_k$ is the coefficient of kinetic friction.

Step3: Calculate the applied force

Given $\mu_k = 0.3$ and $N = 40\ N$, we substitute these values into the formula: $F=\mu_kN=0.3\times40\ N = 12\ N$.

Answer:

12 N