Final answer:
Under the hypothetical scenario where air resistance is independent of speed, the power delivered to the wheels will remain at 20 hp even when the car's speed doubles from 15 m/s to 30 m/s.
Step-by-step explanation:
If the air resistance a car encounters is independent of its speed and it delivers 20 hp to its wheels at 15 m/s, when the car travels at 30 m/s, considering only the given information, the power delivered will remain the same because the air resistance is not dependent on speed.
It's important to note that this is a hypothetical scenario not commonly found in reality because air resistance is almost always a function of speed. Since the resistance is constant regardless of speed, no additional power would be required to maintain a higher speed. Therefore, the power delivered to the wheels when the car is traveling at 30 m/s will still be 20 hp.