The cup without a lid is an example of an OPEN SYSTEM, where things can move in and out of the system. What was moving out of the cup with no lid?
Develop a model to answer the question:
What is happening to the liquid water that can explain why the mass of the cup system with no lid decreases over time?
Draw a zoomed-in view of the surface of hot water in a cup with no lid.
Use your model to make a prediction: If we left this system out in the room overnight, do you think the system would have the same amount of water in it tomorrow as it does right now? How about a week later? Why?
An OPEN SYSTEM lets things go in and out. What would you call a system where nothing gets in our out? (like the cup with lid almost is).
Which of the following best describes what happens?
Explain how you chose your answer above.