Final answer:
The coefficient of kinetic friction is calculated using the frictional force (3.5 N) divided by the normal force (39.24 N), resulting in approximately 0.089.
Step-by-step explanation:
To find the coefficient of kinetic friction (μk), we use the formula that relates frictional force (f k) and the normal force (N): f k = μk N.
Since the object has a mass of 4 kg, its weight and therefore the normal force on a horizontal surface is N = m * g = 4 kg * 9.81 m/s².
Calculating the normal force yields N = 39.24 N.
The frictional force given is 3.5 N.
To find the coefficient of kinetic friction, we rearrange the formula to μk = f k / N.
Plugging in the values, we get μk = 3.5 N / 39.24 N, which yields μk ≈ 0.089.