108. How does water move toward your mouth through a straight straw if you don't suck on the straw?
If the straw is horizontal and the water wasn't moving to begin with, it won't move toward your mouth unless you suck. To make the water accelerate, it must experience net force and the two ways to achieve that net force are (1) to create a pressure imbalance on the water's ends and (2) to have the water's weight accelerate it. In a horizontal force with no pressure imbalance on it, there is no net force on the water and it doesn't accelerate.