Final answer:
The net force acting on the 1000-kg car moving down a 30-degree slope at a constant speed is 0 Newtons, due to the absence of acceleration and the forces being balanced.
Step-by-step explanation:
The question pertains to a 1000-kg car moving down a 30-degree slope at a constant speed of 20.0 m/s. To determine the net force acting on the car, the principles of Newton's laws of motion are applied. As the car is moving at a constant speed, it means that the acceleration of the car is zero. According to Newton's first law, also known as the law of inertia, an object in motion will stay in motion with a constant velocity, and an object at rest will stay at rest, unless acted upon by an external force. In this scenario, the car is continuing at a steady pace, which implies that there is no net force acting on it because the forces are balanced. Therefore, the net force on the car is 0 Newtons (Option a.).