At some angle θk, the object will keep moving, at a constant velocity. (Tipping the incline up farther will cause the object to accelerate; you want the angle at which the object moves dow...At some angle θk, the object will keep moving, at a constant velocity. (Tipping the incline up farther will cause the object to accelerate; you want the angle at which the object moves down the incline at constant velocity, without accelerating.) Once again in this case the acceleration of the object is zero, and the analysis follows just as with the static case.
