Physics 1090: Fundamentals of the Physical Universe

University of Wyoming

Unit 4: Fluids
Due September 23, 2009
20 points

To receive credit, your completed assignment must be submitted to me by the beginning of class on Wednesday, September 23.

Do one, and only one, of the following:

1. Flat tire.

If a car tire loses pressure, it flattens onto the pavement. Why? Explain what is happening in terms of pressure, force (weight is a force), and area.

2. Balloon mash.

When you did the “balloon mash” activity in class, you probably saw that the weight/area ratio increased as the weight on top of the balloon increased. Why did it do that?

3. Fountain.

How vigorously a stream of water shot from a hole in the side of a can depended only on the depth of the hole below the surface of the water. It did not matter how wide or narrow the can was, or what shape the can was, or if there were rocks in the can. Why was this?

To fully answer this question, you need to explain what one factor determines how far the stream of water spurts, and why that depends only on depth below the waterline.

4. Flotation.

Why do some things float on water, but others do not? Yes, things with a density less than that of water float and things with a density greater than water sink, but why will they float or sink?

5. Diver.

When you squeezed the 2-L bottle hoding the floating test-tube diver, the test tube sank. What made it sink?

To fully answer this question, you need to explain why the diver floated in the first place, and what changed to make it sink.

Take your choice of these tasks. Do not submit answers to more than one of them. Just choose one, and submit it. Your answer should thoroughly address all points of the question. An adequate answer will be several paragraphs long.

Warning: Do not turn in paper that has ragged edges! If you write your work in a spiral-bound notebook, trim the edge before submitting it. Papers with ragged edges will be returned unmarked.