1. Closed system: The car and the roadway can be considered a closed system since no external forces are acting on the system as a whole. The only forces present are the internal forces between the car and the roadway.
2. Conservation of momentum: The total momentum of the car-roadway system remains constant unless acted upon by an external force. This implies that the car's momentum (mass times velocity) plus the momentum of the roadway (which is negligible due to its large mass) remains unchanged.
3. Forces acting on the car: The main forces acting on the car are:
- Friction: The frictional force between the car's tires and the roadway opposes the car's motion and causes it to slow down if no other forces are applied.
- Engine force: The force generated by the car's engine acts in the forward direction and propels the car forward.
4. Equations of motion: The motion of the car can be described by Newton's second law, which states that the acceleration of an object is directly proportional to the net force applied to it and inversely proportional to its mass. In this case, the net force is the difference between the engine force and the frictional force.
5. Equilibrium: When the engine force and the frictional force are equal, the net force is zero, and the car moves at a constant velocity. This state is known as equilibrium.
6. Energy considerations: The car's kinetic energy (energy due to motion) and potential energy (energy stored due to its position) are important in analyzing the car's motion. As the car moves, its kinetic energy changes due to the work done by the engine force and the frictional force.
Overall, understanding the system of a car moving on a flat roadway involves analyzing the forces acting on the car, applying Newton's laws of motion, and considering energy transformations that occur during the car's motion.
