Bill Shanks [Joliet West Physics,
More Power 2 U!
Bill noticed that the Shop.Vac® wet-dry vacuums were very powerful indeed, in that the manufacturer apparently advertised product #971-01-00 as having a peak power of 1.5 to 3 Horsepower, while requiring an electric current of only I = 6 Ampères at V = 120 Volts. Indeed, such an assertion appears on the Shop Vac web page, http://www.shopvac.com. Bill showed by direct calculation that 1 Horsepower = 550 ft lb/sec = [550 ft lb/sec] ´ [0.304 m/1 ft] ´[ 9.8 Nt /2.205 lb] = 746 Watts. The input electrical power P = V ´ I = [120 Volts] ´ 60 Amps = [720 Watts], so that this vacuum system is a very remarkable one, indeed, since it can produce at least [1.5 Horsepower] ´ [746 Watts/Horsepower] = 1119 Watts.. Bill also mentioned that a 5 Horsepower Shop Vac required only 8 Amp at 120 Volts, an even more remarkable device! [Porter Johnson pointed out that the European standard horsepower is only 735 Watts, which still did not explain the discrepancy!] It appears that you have solved the energy crisis for once and for all, Bill!
Ann Brandon [Joliet West, Physics]
Ann brought in Pasco Projectile Launcher Projectile Mini-Launcher ME-6825, which shoots small ball bearings. [The more powerful model , ME-6800, which shoots plastic balls, is also available; for details see the Pasco Website http://store.pasco.com/.] The Mini-Launcher has three settings, and we shot the balls with the most energetic setting. First she launched the projectile horizontally at a height of 94.5 cm from the floor, and we measured the distance it traveled before striking the floor to be 2.36 meters. Since the ball took a time Ö (2 h/g) = Ö (2)(.945)/(.98) = 0.43 seconds to hit the ground, it left the muzzle at a speed of 5.4 m/sec. She then launched the ball at an angle of 60º to the horizontal, and measured its horizontal distance of travel back to the launch table, obtaining the range R = 2.48 meters. Ann compared this with the range formula R = v02 sin 2 q /g = 2.50 m.
Ann also mentioned the following items:
Alder delivers a triple whammy with this elegant history of technology, acute cultural chronicle and riveting intellectual adventure built around Delambre's and Mechain's famed meridian expedition of 1792-1799 to calculate the length of the meter. Disclosing for the first time details from the astronomers' personal correspondences (and supplementing his research with a bicycle tour of their route), Alder reveals how the exacting Mechain made a mistake in his calculations, which he covered up, and which tortured him until his death. Mechain, remarkably scrupulous even in his doctoring of the data, was driven in part by his conviction that the quest for precision and a universal measure would disclose the ordered world of 18th-century natural philosophy, not the eccentric, misshapen world the numbers suggested. Indeed, Alder has placed Delambre and Mechain squarely in the larger context of the Enlightenment's quest for perfection in nature and its startling discovery of a world "too irregular to serve as its own measure." Particularly fascinating is his treatment of the politics of 18th-century measurement, notably the challenge the savants of the period faced in imposing a standard of weights and measures in the complicated post-ancien regime climate. Alder convincingly argues that science and self-knowledge are matters of inference, and by extension prone to error. Delambre, a Skeptical Stoic, was the more pragmatic and, perhaps, the more modern of the two astronomers, settling as he did for honesty in error where precision was out of reach. Copyright 2002 Reed Business Information, Inc.
Good stuff, Ann!
Fred Schaal [Lane Tech HS, Mathematics]
Riding the Rails --- Again!
Fred continued to describe his rail travels around the country, indicating that in a number of passenger stations there engines of ancient vintage on display. He saw the legendary Union Pacific Big Boy 4884 steam locomotive in one station; for details on that engine see the Union Pacific Big Boys website http://www.steamlocomotive.com/bigboy/. There were also a number of diesel locomotives of ancient vintage on display.
Fred asked why there were different couplers on tank cars, which were much higher off the ground. It was suggested that such an arrangement would decrease the likelihood of punctures of tank cars during train wrecks, since hazardous materials are routinely transported in tank cars. Porter Johnson mentioned that the coupling mechanism on American trains [from Tierra del Fuego to Valdez; automatic coupling] is different from that on European trains [mechanical coupling with hydraulic plungers to maintain stability], whereas Lego®.Trains use magnets for coupling. For additional information see the website Military Traffic Management: http://www.tea.army.mil/DEP/TRANSPORT/modes/rail/nylon.htm. You seem to enjoy hearing the squeal of the train wheels, Fred!
Leticia Rodriguez [Peck School] Cardiostrides:
Aerobic Gym Shoes
Leticia has been trying out new shoes, to wear in comfort while obtaining aerobic exercise in the process.. She showed us her new Cardiostride shoes, which are described on the Team Nikken website at locations http://www.e-nikken.com/cardiostrides/ and http://www.e-nikken.com/cardiostrides/whycardio.htm. The shoes look comfortable, and Leticia said they increase heart rate to burn more calories through aerobic exercise. Most interesting, Leticia!
Roy Coleman [Morgan Park HS, Physics]
The Wicked Witch of the South Side [Hallowe'en is
Roy, along with his accomplice Lee Slick, took photos of SMILE participants in the levitation apparatus. For similar photos of 1997 participants, see the SMILE website photos97.html. Roy also circulated a Smart Home Catalog, that should meet all our needs for Halloween Horror. For example, "Greet "trick or treaters" and party guests with awesome outdoor gear!" or "This vicious and evil looking wolf has piercing red eyes and gargantuous fangs that say nothing more than this pet is ready for dinner!" The Catalog is available on the website http://www.smarthome.com/halloween2002.html.
As a sequel to Roy's very informative and unusual lesson, Bill Blunk presented us the following Physics Riddle:
Q: What happens when you cross a mountain climber with a mountain goat?
A: You can't cross them, because they're scalers!
Ben Butler [Laura Ward Elementary School, K-8
Hip-hop changes in units.
Ben showed us how to go from inches to centimeters by multiplying by the ratio 2.54 cm / 1 inch = 1 [Part 1], as well as to reverse the process by multiplying by 1 inch / 2.54 cm =1 [Part 2]. Ben knew that this idea would work very well in class in converting 14 inches to centimeters, or 40 centimeters into inches. But, for the long term, it would go in one ear and out the other for most students, and he found a way to make the point more memorable by converting the message into a rap chant:
It takes two partsVery clever, Ben!
I need two parts
To multiply by the number one.
[... This is repeated with a rap rhythm. ...]