posted by POPCORN .
IN THIS EXPERIMENT YOU FILL A PREFROM WITH WATER AND PUT A DRINKING STRAW INTO THE PREFROM AND USE CLAY TO SEAL THE OPENING.
It is important to recall that when you first tried it, you were unable to drink, but a small amount of water entered the straw. When the water goes into the straw, what happens to the volume of water in the sealed bottle? How is this related to the properties (P,V) of the gas above the water?
I've not done this experiment but I assume if water enters the straw that the water level in the bottle will decrease, the volume of air above the water must increase, and the pressure must decrease.