Answer
(a) The net force acting on the sleigh is zero.
(b) $\mu_k = \frac{T}{mg}$
Work Step by Step
(a) The sleigh is moving at a constant speed. Therefore, the net force acting on the sleigh is zero.
(b) Since the net force on the sleigh is zero, the force of kinetic friction must be equal in magnitude to the force applied on the sleigh by the horse. We can find the coefficient of kinetic friction:
$F_N~\mu_k = T$
$\mu_k = \frac{T}{F_N}$
$\mu_k = \frac{T}{mg}$
