Seasickness: Kill or Cure - S3-E24
Question: Why does a separated bubble form when you drive with your tailgate up?
Question: The gorilla is said to possibly be able to lift two family cars, which weighs over 2090kg. If it can, then why is it only number 8 in the countdown while the rhinoceros beetle is number 1?
Answer: They based it on how much they can lift in relation to their body weight. A Rhinoceros Beetle can lift 850 times its own body weight, which would be equivalent to a Gorilla lifting 255 tons (over 100 times more than 2,090 kg).
Answer: A more complex and complete answer probably isn't possible here, since we're dealing with fluid dynamics, pressure, boundary levels, etc. A simply answer would the air in the bed is kept there by the fast moving air coming off the roof of the cab. If there was no "secondary bubble" of air, you would have a vacuum in the bed. When air comes off the roof, it needs a place to touch down, which it is able to do with the top of the tailgate. The fast flowing air moving over the bed keeps the air that's already inside the bed from "escaping." However, the air in the bed is still moving and creates a vortex in the bed, which is described as a bubble. When the tailgate is down, the air coming off the roof will gather at the back of the cab and create drag.
Bishop73