Question

question 9 of 10 the coefficient of kinetic friction between a couch and the floor is 0.81. if the couch has a mass of 71 kg and you push it with a force of 650 n, what is the net force on the couch as it slides? a. 696 n b. 46 n c. 331 n d. 86 n

Explanation:

Step1: Calculate the normal force

The normal force $N$ on a horizontal - surface is equal to the weight of the object. Using $N = mg$, where $m = 71\ kg$ and $g=9.8\ m/s^{2}$. So $N=71\times9.8 = 695.8\ N$.

Step2: Calculate the kinetic - friction force

The formula for the kinetic - friction force is $F_f=\mu_kN$, where $\mu_k = 0.81$ and $N = 695.8\ N$. Then $F_f=0.81\times695.8=563.6\ N$.

Step3: Calculate the net force

The net force $F_{net}$ is the applied force $F$ minus the friction force $F_f$. Given $F = 650\ N$ and $F_f = 563.6\ N$. So $F_{net}=F - F_f=650 - 563.6 = 86.4\approx86\ N$.

Answer:

D. 86 N