Final answer:
The propulsion force on a car is mainly provided by engine power, with the tires interacting with the road surface through friction. This force allows the car to overcome opposing forces like air resistance and, in some cases, can be aided by gravitational pull on slopes.
Step-by-step explanation:
The propulsion force on a car is due to engine power. This force is generated by the car’s engine, delivering power through the drivetrain to the wheels. The wheels exert a backward force against the ground, and due to Newton’s third law (every action has an equal and opposite reaction), the ground exerts an equal and opposite force forward, propelling the car. This interaction is fundamentally based on friction between the tires and the road surface. Without friction, the tires could not push back against the road to move the car forward.
It’s important to note that while propulsion is caused by the car’s engine power, the car must overcome various opposing forces to maintain motion. One example is air resistance, which increases with the vehicle’s speed, requiring more power from the engine to maintain speed. Additionally, while the gravitational pull does not directly provide propulsion, it can contribute to the car moving when going downhill, with gravity aiding forward motion.