Final answer:
Passing a commercial vehicle takes more care than a passenger vehicle on a level highway due to air pressure differences, as when a car overtakes a truck, a lower pressure zone is created between the two, causing them to be pushed together.
Step-by-step explanation:
Passing a commercial vehicle as opposed to a passenger vehicle on a level highway requires more care and attention due to the effects of air pressure and turbulence. According to the provided figures, when a car is passing a truck, the air passing between them must speed up because the space is narrower, a phenomenon explained by Bernoulli's principle. As the speed of the air (v2) increases, the pressure (P1) between the vehicles drops compared to the ambient pressure (Po).
This change in pressure can cause a force that pushes the car and the truck towards each other, often surprising to drivers. Therefore, it is imperative for the safety of all road users to give commercial vehicles plenty of space and pass quickly and efficiently to minimize the time spent in this lower-pressure zone. Additionally, the high profile of commercial vehicles means they can block the view of the road ahead, requiring the overtaking driver to ensure it is safe to pass and complete the maneuver without excessive speed.
It's apparent that understanding the principle of air pressure differences around large vehicles can assist in safer decision-making on the highways. Those driving smaller vehicles should be aware of these dynamics when overtaking to avoid potential collisions.