Final answer:
To maintain a constant velocity, the forces generated by the car engine must equal the total resistive forces. The magnitudes of drag forces depend on the speed of the vehicle and its specific characteristics. Newton's first law applies, stating that the net force on a car at constant velocity is zero.
Step-by-step explanation:
To maintain a constant velocity, a car needs to generate a force that matches the total resistive forces acting against it, which includes both drag force and friction. In the case of a Toyota Camry with a drag area of 0.70 m² and a Hummer H2 with a drag area of 2.44 m², the magnitudes of the drag forces vary according to the speed of each vehicle. At 70 km/h and 100 km/h, these magnitudes can be calculated using the drag coefficient, air density, and the velocity squared. The net force on a car moving at constant velocity is zero, as described by Newton's first law of motion. When a car is accelerating, the net force is non-zero, resulting in a change in velocity.