Answer: μk=0.3896
Explanation: the formula for the coefficient of kinetic friction is μk=fs/n
In other words, the coefficient of kinetic friction is equal to the kinetic friction divided by the normal force. In this equation, the kinetic force is equal to the 840 N of force and to find the normal force you will take the weight of the couch, 220 kg, and multiply it by the acceleration of gravity which is always going to be 9.8 m/s^2. It should look like this… N=(220 kg)x(9.8 m/s^2)=2,156
So the normal force equals 2,156
Now you can continue to solve for the coefficient of kinetic friction by using the formula I gave earlier μk=fs/n and plugging your numbers in
μk= 840N/2,156
μk=0.3896