Final answer:
The uneven air pressure created when a car window is lowered causes empty plastic bags to fly out due to the principle of air pressure and aerodynamics. A 2 inch gap between bags and the cargo bin ceiling likely serves to allow airflow, preventing the bags from shifting or flying out due to pressure differences.
Step-by-step explanation:
The question refers to the principle of air pressure and aerodynamics within the context of physics. When a car is in motion and the window is lowered, the air pressure inside the car becomes uneven with high pressure outside and lower pressure inside.
This is due to the faster-moving air outside the car creating a lower pressure area in accordance with Bernoulli's principle. Consequently, any lightweight object like an empty plastic bag can be swept up by the higher pressure air and carried out through the window as the air inside the car moves towards the area of lower pressure to equalize the pressure difference.
The importance of keeping a 2 inch gap between bags and the cargo bin ceiling likely concerns allowing for sufficient airflow. This helps prevent the sudden shift in air pressure from causing bags to move or fly out unexpectedly in various transportation scenarios, mirroring the effect seen with the car window example.