A student completely fills a plastic syringe with water, removes all air bubbles, and seals the tip. The student then steadily increases the force on the plunger with her thumb, but observes virtually no change in the volume of water inside the syringe while the required force rises sharply.
Respond to the following prompts about this observation.
(a) Describe, in terms of molecular interactions, how pressure is exerted by a liquid on the interior walls of its container.
(b) Explain why a substantial increase in the applied force produces a large increase in the internal pressure of the water but does not produce a noticeable change in the volume of the water.
(c) Predict how both the internal pressure change and the volume change would differ if the syringe were filled with air at atmospheric pressure instead of water, and justify your reasoning qualitatively.