Question

Why bottle gets compressed?

Answer 1

Answer:

because of air pressure

Answer 2

Explanation:

Bottle gets compressed?

If you open up your water bottle and drink the water air will have to replace the volume of water.  If you do that at cruising altitude and then put the cap back on the bottle, you will have a plastic bottle full of air at 10.9 psi (75.3 k Pa).  That's no big deal while you're still at cruising altitude, but when the plane comes back down to sea level and the cabin pressure increases to 14.7 psi (101 kPa), there is now an imbalance. There is air outside the bottle pushing in at a higher pressure than the air inside the bottle is pushing out.  So, the bottle can compressed