I would let someone more confident in this field to answer this question but that sounds like a Chemical reaction
Answer:
The quantum theory
Explanation:
The theory that assumes that energy exists in individual units called quanta, in the same way that matter has individual atomic units.
When Jeep is in motion the Canvas top is initially flat
so when Jeep is in motion the air at the top of the Jeep is in high speed
while the air inside the jeep is not moving that fast
so as per Bernuolli's Theorem we know
so if we increase the speed the pressure will decrease
so the canvas will experience less pressure at the top of canvas while at the bottom it will have more pressure from inside
so the Canvas will bulge outside or curved outside