Question

1. when a horizontal force of 30 n acts upon a 5kg - object on a rough surface, as shown in the figure, the object moves with a constant velocity. find the coefficient of kinetic friction, $mu_{k}$ between the object and the surface. (take $g = 10n/kg$)

Explanation:

Step1: Analyze the forces

Since the object moves with constant velocity, the net force is zero. The horizontal force \(F = 30N\) equals the kinetic - friction force \(F_f\). So \(F_f=\mu_k N\), and the normal force \(N = mg\) (where \(m = 5kg\) and \(g = 10N/kg\)).

Step2: Calculate the normal force

Using the formula \(N=mg\), substitute \(m = 5kg\) and \(g = 10N/kg\).
\(N=5\times10 = 50N\)

Step3: Calculate the coefficient of kinetic friction

Since \(F = F_f=\mu_k N\), then \(\mu_k=\frac{F}{N}\). Substitute \(F = 30N\) and \(N = 50N\).
\(\mu_k=\frac{30}{50}=0.6\)

Answer:

\(0.6\)