Answer
(a) static
(b) $0.50$
Work Step by Step
(a) From the given information, we can determine the coefficient of static friction. This is because initially the bulldozer is at rest and the friction associated with a body at rest is static friction.
(b) We know that
$\mu_s=\frac{Kx}{mg}$
We plug in the known values to obtain:
$\mu_s=\frac{(13)(0.45)}{1.2(9.81)}$
$\mu_s=0.50$
