cases, it is easiest to define the horizontal (or x direction) as being parallel to the slope and the vertical (or y direction) as being perpendicular to the slope. The first force to consider is the weight of the object. Gravity always acts toward the center of the Earth, so the force due to gravity does not lie along one of the axes of this problem. Therefore, it is necessary to break down the force into its components using trigonometry and the given angle of the hill. Since the object is not accelerating in the y direction (it remains on the surface of the inclined plane), the normal force exerted by the surface of the plane must equal in magnitude the y component of the force due to gravity. Since the normal force has no horizontal component, there is a net force and acceleration of the object down the hill. The net force is equal to the x component of the force due to gravity. This problem is explicitly solved in the inclined plane section.
