PY 195 Freshman Physics Seminar (Fall 2012)

Course Information (including weekly reading assignments and my office hours) (updated Aug. 23)

WEEKLY READING ASSIGNMENTS:

Reading for the week of Sept. 3: text up to section 1.40.
Discussion item for class on Sept. 6: Here are time-lapse photos (1,2,3,4,5) of the blast wave from first atomic bomb test in July 1945.
What was the energy released by this blast?

Reading for the week of Sept. 10: Text, section 1.41-118. Focus on sections 1.49-53 and 1.73-77 and be prepared to discuss these two topics in class.
    Discussion items for class on Sept. 13:
        1. Here is a movie of a masse shot. What is the cue ball trajectory?
        2. An object falls in air due to gravity. How does the terminal speed depend on g, air density, and object shape?
        Sketches of fluid flow past an obstacle for different flow speeds, and the drag force on a cylinder versus flow speed (Feynman Lectures on Physics vol. II.

Reading for the week of Sept. 17: Finish chapter 1 of the text. Please focus on sections 1.24, 1.42, and 1.45, and be prepared to discuss these topics in class.
(Homework/discussion items for class on Sept. 20:

Fill a glass to the brim with water and walk with it. Can you do so without spilling the water? What happens when you try the same thing using a shallow pan whose radius is a foot or more? (Perhaps you should try the second experiment outside.)

What is silly putty made from? If you have some, play with it and then answer the following question: Is silly putty a liquid or a solid?

Crumple some standard sheets of paper to as small a ball as you can. Uncrumple your samples and study the pattern of folds. What can you learn from this pattern?

On a single sheet of paper with your name on it, please provide one general question about physics that you would like to know the answer. Please turn in this paper by Wednesday at 4pm. You can either give it to me when I'm in my office SCI 321, or slip it under my office door if I'm not there.

Reading for the week of Sept. 24: Text, up to section 2.68. Please focus on 2.10, 2.25, and 2.26, and be prepared to discuss these topics in class.

For fun, here are a few photos from the book "An Album of Fluid Motion" by M. Van Dyke on fluid flow patterns around a cylinder/sphere for various Reynolds numbers.

Homework/discussion items for class on Sept. 27:

Take a sheet of standard white paper and try to shape it to make it fall as slowly as possible in air when released from 5 ft about the ground. You can fold it and/or cut to to any shape or size (as long as it is larger than 1 square cm). Please bring your creation to class and demonstrate it. A brownie point will be given to the design with the longest fall time.

On a single sheet of paper with your name on it, please provide one question about physics that you would like to know the answer. Please turn in this paper by Wednesday at 4pm. You can either give it to me when I'm in my office SCI 321, or slip it under my office door if I'm not there. Please be forewarned that 0.3 of a grade point will be deducted if a question is not turned in.

Reading for the week of Oct. 1: Please finish reading chapter 2. There is a wealth of fascinating phenomena discussed that could occupy an entire course. Please focus on the following topics: 2.75 (splashing), 2.81 (pearling instability), 2.84 (drop spreading), 2.85 (cheerios attraction), 2.91 (coffee stains), 2.102 (sand cohesion), 2.107 (sand flow in an hourglass), 2.121 (dripping faucet), 2.137 & 138 (convection instabilities).

Homework/discussion items for class on Oct. 4:

If you eat cheerios, please perform the experiment of section 2.85.

On a single sheet of paper with your name on it, please provide one physics question on the topics from chapter 2 highlighted above. Please turn in this paper by Wednesday at 4pm. You can either give it to me when I'm in my office SCI 321, or slip it under my office door if I'm not there.

For your viewing pleasure: this movie shows the splash of a liquid drop when it hits a flat solid surface with either 1 atm (left) or 0.2 atm (right) pressure. The movie was taken from a research page of Prof. Sid Nagel at the University of Chicago.

Reading for the week of Oct. 8: Please read chapter 3. Please focus on sections 3.61-3.70. There will be a short 10-minute quiz in class this Thursday, Oct. 11 on dimensional analysis.

Homework/discussion items for class on Oct. 4: On a single sheet of paper with your name on it, please provide one physics question on either the topics from chapter 3 or anything in physics. It should be your own personal question and not just something from the book Please turn in this paper by Wednesday at 4pm. You can either give it to me when I'm in my office SCI 321, or slip it under my office door if I'm not there.

Here is a u-tube video that was suggested by Alex Oleinik:

The description given here is from the u-tube video.

Honey is dribbled off the end of a chopstick into a pot below. As the falling stream stikes the pool of honey below, it turns itself into tight circular coils which rapidly begin to pile one on top of the other. A growing column of liquid coils of rope begin to emerge from above the surface of the honey in the pot in an effect referred to as the liquid rope-coil effect.

Uneveness in the amount of sinking at the base of the growing column of coils causes it to collaspe before a new column of liquid coils re-emerge and begin to rise up again.

The rate of coiling is increased as the height from which the honey is allowed to fall from is raised.

Here is a u-tube video that was suggested by Tim Chiang:

The description given here is paraphrased from the u-tube video.

When the slink is released, its center of mass accelerates downward (like any falling object). Because the slinky is stretched when it is released, the slinky also compresses towards its equilibrium (relaxed) length. This means that top and bottom of the slinky are accelerating towards the center of mass of the slinky at the same time the center of mass is accelerating downward.

What is apparently miraculous is that these two effects cancel so that the bottom of the slinky remains at rest for a finite time.

Reading for the week of Oct. 15: Please read chapter 4 up to section 4.50. Please try the experiments related to section 4.6 (the liquid drop on a hot skillet, and not sticking your finger in molten lead) 4.20. This winter, please try the experiments related to sections 4.33 and 4.34. Finally, a question for class related to section 4.23: if the outside temperature is much below freezing, how quickly does an ice layer form on a pond. My concrete question: what is the dependence of the ice thickness on time?

Homework/discussion items for class on Oct. 18: On a single sheet of paper with your name on it, please provide one physics question on either the topics from chapter 4 (up to section 4.50) or anything in physics. It should be your own personal question and not just something from the book. Please turn in this paper by Wednesday at 4pm. You can either give it to me when I'm in my office SCI 321, or slip it under my office door if I'm not there.

Here is a u-tube video that was suggested by Enze Yan:

This shows the bizarre flow patterns in a ferrofluid. A ferrofluid is a liquid that contains ferroamagnetic particles. When a time-varying magnetic field is applied to the fluid, the resulting flow patterns can be extremely rich.

Reading for the week of Oct. 21: Please finish reading chapter 4 of the text. Please do the experiment mentioned in section 4.86. I also found a recent article about scaling and dimensional analysis in physics that I think is accessible and fun to read. As part of your weekly reading assignment, please also read this article.

Here is another u-tube video that was suggested by Enze Yan:

This shows a Lichtenberg figure thait is created by a nail being taped on a piece of plastic. In just a few hundred nanoseconds, electrons trapped in plastic exit suddenly as a bright, branching spark. The first 5 sections of this video are the most interesting.

Reading for the week of Oct. 29: Please read chapter 5 of the text up to section 5.28. Please also read this essay that presents some simple ideas about the right size of various organisms.

Homework for class on Nov. 1: On a single sheet of paper with your name on it, please provide one physics question on either the topics from chapter 5 (up to section 5.28) or anything in physics. It should be your own personal question and not just something from the book. Please turn in this paper by Wednesday at 4pm. You can either give it to me when I'm in my office SCI 321, or slip it under my office door if I'm not there.

Reading for the week of Oct. 29: Please read chapter 5 of the text up to section 5.28. Please also read this essay that presents some simple ideas about the right size of various organisms.

Reading for the week of Nov. 5: Please finish reading chapter 5 of the text.

Homework for class on Nov. 8: On a single sheet of paper with your name on it, please provide one physics question on either the topics from chapter 5 (up to section 5.28) or anything in physics. Please turn in this paper by Wednesday at 4pm. You can either give it to me when I'm in my office SCI 321, or slip it under my office door if I'm not there.

Reading for the week of Nov. 12: Please read chapter 6 of the text up to section 6.59.

Homework for class on Nov. 15: On a single sheet of paper with your name on it, please provide one physics question on topics from chapter 5, up to section 6.59. Please turn in this paper by Wednesday at 4pm. You can either give it to me when I'm in my office SCI 321, or slip it under my office door if I'm not there.

Additional resources: Ryan Gelly brought to my attention some useful and easy-to-read material associated with the MIT course "Stree-Fighting Mathematics". One particular section of the text that is especially nice is here. Although this course is mostly on mathematics rather than on physics, the types of problems and problem-solving methods presented in this chapter are not far from some of the material in PY195. I invite you to take a look at this chapter.

Here is a u-tube video that was suggested by Blaze Travis:

The video shows the head-on collision of two vortex rings. After the rings meet, there is a subsequent breakup of the vortices into progressively smaller vortices until the process is damped out by viscous effects.