Relating Graphs and Ratios

Activity D3: Density of a Changeable Object

Name: Group: Class Period:

	What happens to the density of a changeable object?
	1. A can of soda can be thought to be made up of the aluminum of the can itself, the soda inside, and the air (gas) in the can. The total mass is the combined mass of all the stuff. The total volume is the combined volume of all the stuff. By dividing the total mass by the total volume for the whole object, we could get a density number expressed in gm/ml for the object. If we pour out some of the liquid, more air rushes in to take its place. How would various properties of the can of soda with some liquid poured off compare with those of the full can? Explain your answers.
	Compared to the full can, the partial can:
	The total mass would be (greater than, less than, or same as) the full can.
	The total volume would be (greater than, less than, or same as) the full can.
	The density would be (greater than, less than, or same as) the full can.
	2. Suppose instead, we thought of the can of soda as made up only of the aluminum and the liquid soda and didn't include the air (gas) inside. How would various properties of the partially poured out can of soda compare with the full can? Explain your answers.
	Compared to the full can, the partial can:
	The total mass would be (greater than, less than, or same as) the full can
	The total volume would be (greater than, less than, or same as) the full can.
	The density would be (greater than, less than, or same as) the full can.
	3. Summarize how thinking of the object differently can change the answers to the questions.
	4. Summarize how changing the object (e.g. pouring out liquid) can change the density of the object.
	5. Would the graph of the mass vs. volume of either scenario in number 1, or the scenario in number 2, come out approximately straight? Why or why not? (Hint: Think of starting with no liquid in the can and adding a little bit at a time, measuring the mass and the volume, add a bit more, measure, etc. until the can is full.)
	6. Summarize any new issues and ideas and place them in the appropriate Idea Journal(s).