Answer:
(a) [tex]\mu_s=0.25[/tex]
(b) [tex]\mu_k=0.20[/tex]
Explanation:
According to Newton's second law:
[tex]\sum F_y:N=mg\\\sum F_x:F_a=F_f[/tex]
Recall that the frictional force is related jointly with the coefficient of friction and normal force [tex]F_f=\mu N[/tex]. Replacing in the above equation, we get the coefficient of friction:
[tex]F_a=\mu N=\mu mg\\\mu=\frac{F_a}{mg}[/tex]
(a) The coefficient of static friction is related with the force required to set the block in motion:
[tex]\mu_s=\frac{71N}{29kg*9.8\frac{m}{s^2}}\\\mu_s=0.25[/tex]
(b) The coefficient of kinetic friction is related with the force required to keep the block moving with constant speed:
[tex]\mu_k=\frac{56N}{29kg*9.8\frac{m}{s^2}}\\\mu_k=0.20[/tex]
