Final answer:
The lowest pressure George can maintain in his mouth when sucking water up a long straw is limited by the atmospheric pressure. The maximum pressure difference that can be created allows the water to be drawn up a maximum height of around 10.3 meters at sea level.
Step-by-step explanation:
When sucking water up a straw, the lowest pressure George can maintain in his mouth is determined by the atmospheric pressure. The pressure difference between the atmospheric pressure and the pressure inside the straw is what allows the water to be drawn up. The maximum height the water can reach is limited by the maximum pressure difference that can be created, which is around 10.3 meters at sea level. This is because the atmospheric pressure can support a column of water about thirty feet high.