25 March 2003

Notes Prepared by Porter Johnson

**Porter Johnson**announced that there will be a special lecture at**IIT [111 Life Sciences Building; Math-Physics SMILE classroom]**on**Thursday**16 April at 4 pm. The speaker will be**Professor Michael S Turner of the University of Chicago**, and the talk title is**" ... In the Beginning"**.

Fred

**Very visual and user-friendly, Fred!**

**Larry Alofs [Kenwood HS,
Physics]
Totally Tubular!
Larry** placed

Specifically, the[BOM-100 Basic Boomwhacker Set -$31.95]: These eight labeled tubes produce theC-Major Diatonic Scale. The end-caps lower the tones by one octave. Included in package: eight tubes, long with removable end caps."These brightly colored, tuned percussion tubes are great for teaching students, of any age, about sound. When whacked against your knee or the floor each produces a particular note. The longer the tube, the lower the note. Each tube is color-coded and labeled with its precise note. When the tube is closed at one end with a cap (available with tubes and separately, see below), the note shifts an octave lower.

Boomwhackerswere invented byCraig Ramsellwhen he noticed that cardboard tubes from wrapping paper could be used to produce music. These tubes are amazing, loads of fun and very educational. Put a class set together and compose your next science sound lesson!"

Note |
Length Calculated |
Length after Tuning |

C |
(63.0 cm) |
63.0 cm |

C^{#} - D^{b} |
- |
- |

D |
56.1 cm |
56.1 cm |

D^{#}- E^{b} |
- |
- |

E |
50.0 cm |
49.8 cm |

F |
47.2 cm |
46.9 cm |

F^{#}- G^{b} |
- |
- |

G |
42.0 cm |
41.5 cm |

G^{#}- A^{b} |
- |
- |

A |
37.5 cm |
36.9 cm |

A^{#}- B^{b} |
- |
- |

B |
33.4 cm |
32.2 cm |

C |
31.5 cm |
30.3 cm |

The calculated lengths were obtained from the first number (**63.0
cm**)
by dividing (once or twice, as appropriate) by the factor **2 ^{1/12
}= 1.05946 ... **, as required for the

**Larry** next pointed out that, for pipes of resonating air with
one end closed,
the pipe length is given in terms of the wavelength **l **
by** L = l /4**. In other words,
for a given pipe, the wavelength would be
reduced by a factor of** 2**, and the frequency **f **would
double, in
going from two open ends to one open end. By striking the
end of the
pipe against his hand, **Larry** demonstrated this octave
shift. While
several of us held the pipes, **Larry **played the tune **Mr Frog**,
which
was the first piece he learned to play on a piano. Not to be left
behind
in this musical extravaganza, **Don Kanner** illustrated the West
African **
Shantu** [http://www.billabbie.com/nigeria/music.htm]
instrument, hitting the pipe on his thigh. It produces an
interesting sound, but it seems likely to leave bruises. For details
see
**Exploring Music: The Science and Technology of Tones and Tunes**
by
Charles Taylor [Institute of Physics, 1992, **ISBN:** 0-7503-02135]

**Larry, you make "fairly" beautiful music while showing very
beautiful physics!**

**Katherine Hocker [Bloom Trail HS,
Physics]
Home-made Spectroscope
Katherine** expressed frustration with traditional spectroscopes, in
that
students took almost a full lab period to be able to see simple
diffraction
images, etc. She passed out several of her home-made
spectroscopes, with a

**Pretty stuff, Katherine!**

**Ben Butler** **[Laura Ward Elementary School, Science
Teacher] **
**What's a Million?
Ben** showed several exercises that he has presented to his students.

- First he showed us two capped containers [about
**2 gallons or 10 liters**] that contained colored, tiny plastic beads. He remarked that each container contained**1 million**individual pieces. The container with**yellow**beads contained**one black bead**. Surprisingly, it was fairly easy to find that bead, since it migrated to the top as we shook the container.**Ben**shook it to the tune of the chorus [**Bounce-Bounce-Bounce-**... ] of the**R Kelly**rap song,**Ignition**. without the lyrics. [**Ben**occasionally does this chant in class, to let the students know that he is not totally ignorant of their world.]**Ben**passed around another container with a million**blue**plastic pieces, and**one black one**, which is much harder to find. - Ben next showed us the mechanism for a bar stool turntable.
First he used it to demonstrate the relation between the radius R
and circumference
**c**of a circle:**c = 2 p R.**He measured the radius (**6" or 15 cm**) with a ruler, and then calculated the circumference. He demonstrated the expression by putting**3**sheets of notebook paper [**11" or 33 cm**each] around the edge, and then showing that he needs just a little more to make the circumference [**37.7" or 96 cm**] **Ben**next had a volunteer to stand on the mechanism, and**Ben**rotated him around several times. He asked us how far the edge of the mechanism had moved in, say, 5 complete revolutions --- more than**15 feet**or nearly**5 meters**. The participant got very dizzy while being spun around,**for some strange reason!**- The volume of a cylinder of radius
**R**and height**H**is**V = p R**, and the area of its lateral surface is^{2}H**A = 2 p R H**. Starting with two**8.5" ´ 11"**transparency sheets,**Ben**folded one into a long,**11" tall**cylinder, and the other into an 8.5" short cylinder. With their bottom ends blocked off, which way cylinder would hold the greater volume? Most students expect that the taller cylinder will have a greater volume than the shorter one. Ben stood both cylinders inside a large transparent container, with the shorter one encircling the taller one. Then**Ben**showed us the answer by using**Uncle Ben's Rice™**to fill the long cylinder completely. He then lifted the long cylinder, so that the rice inside it spilled into the shorter cylinder --- which was then only partially filed with rice.**Ben**was able to add quite a bit more rice in filling the shorter cylinder! In the interest of full disclosure,**Ben**pointed out that he has no relation to either**Uncle Ben™**or his rice!

**A good set of ideas, Ben!**

**Arlyn van Ek [Illiana Christian HS,
Physics]
Magnetic Fluids
Arlyn** show us a

"The material in this fluid device is a Magneto-Rheological Fluid, or MR Fluid. MR fluid is a suspension of micronized, magnetically susceptible (iron/steel) particles in water with suspension additives. Under normal conditions, MR fluid is a free-flowing liquid with a consistency similar to that of very thick motor oil. Thus, the fluid can flow freely between the syringes under pressure from your hand on the piston. Exposure to a magnetic field, however, can transform the magnetically susceptible particles into a near-solid mass in just milliseconds. The solid forms when the particles in the fluid align with the magnetic field lines of the magnet. The space between the particles is diminished and the fluid cannot flow, taking on the properties of a solid mass. The fluid can be returned to its liquid state with the removal of the magnetic field."

**These magnets don't really "go with the flow", Arlyn!
Fascinating!**

**Hoi Huynh
[Mathematics Teacher] Maintaining Balance
in
Mathematics
Hoi** demonstrated that, when a standing cylinder has

**Hoi **pointed out that, of all quadrilaterals that
have a given perimeter **p** , the square has the greatest area, **A
= p ^{2}/16**.
For all shapes of a given perimeter

Hoi also
mentioned that the formula for the **Area of a Trapezoid** of bases
**b _{1}** and

**Thanks for the insights, Hoi!**

**Don Kanner [Lane Tech HS, Physics]
Proclamation Concerning Areas and Volumes**

**Don **remarked that, because the lateral surface area of a
cylinder of radius ** R
** and height ** H** is **A = 2 p
R H**, whereas its volume is **V = p
R ^{2} H**,
it should follow that the cylinder of

** Don**
promised to prove it next time! **We await
edification, Don**!

See you at our next meeting,
**08 April
2003**!

Notes prepared by **Porter Johnson**