May 8th, 2006
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How do you crush a can? With your foot - on your forehead – under your arm? Well, today we crushed cans with the phenomenon of implosion.
Well, Implosion is the violent inward collapse of something onto itself, ultimately resulting in a condensed or crushed state of the original object. This is often used by Engineers to bring down massive structures without the use of a huge wrecking ball and other primitive demolition tools. Another example is a submarine being crushed from the outside by the high pressure of the surrounding water.
Today, we demonstrated this cool technique by using a hotplate, several empty and cleaned soda cans, water and tongs to hold the cans.
First we put only a few drops of water into each can and placed them on the hotplate until we started to see water vapor escaping from the can.
Then we used the tongs to grab the hot can off of the hotplate and placed it into a cold bowl of water with the opening of the can facing directly down (towards the water in the bowl).
POP!
The can imploded.
Okay, what’s happening here? Well, the can was filled with only air before we added the water, and by heating the can the water turned into water vapor and pushed out any air that was originally in the can. When the can was turned upside down and put into the bowl of cold water, the water vapor (gas) inside condensed and turned back into water (liquid), and since the molecules of a gas take up more space than the molecules of a liquid, this pulled the walls of the can inward due to the pressure outside the can becoming greater than the pressure inside.
Tah Dah – a crushed can.
Sources:
http://science.howstuffworks.com/building-implosion1.htm
http://physics.ucsd.edu/was-sdphul/labs/demos/fluids/crushcan.html
http://physics.ucsd.edu/was-sdphul/labs/demos/movies/crushcan.mov
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May 2nd, 2006
While the students continued to work on their towers, we did a quick science demonstration that used the glue that that they were using to make the fun - and an all so popular toy - called silly putty.
Invented in 1943 by a GE engineer named James Wright, and fashioned to look like artificial rubber, he accidentally mixed silicone oil and boric acid together which created a compound that acted much like rubber but with the ability to rebound, stretch and copy almost any image pressed against it. This hardly lived up to what he set out for and they ultimately found no practical use for it other than playing with it. It was originally called “Nutty Putty” until 1949 when it was then called Silly Putty® as we all know it today.
(source: http://inventors.about.com/library/inventors/blsillyputty.htm)
This was simply an example of a chemical mixture designed to create a chemical reaction between a polymer and cross linking response with the borax while using water as a solvent to modify the physical properties of the resulting material.
Now, to translate that into something that even I could understand, our glue is a polymer that flows pretty smoothly when poured, and our Borax powder soap is the agent we use to cross link the molecules and slow down their ability to flow smoothly and lastly, water helps to form some of its physical characteristics.
The recipe is simple, and can be messy, but certainly fun.
White Glue (8 oz)
Borax (powdered soap) (1 - 2 teaspoon(s))
Warm Water (4 - 8 oz)
Combine and stir the borax and water and add it to the white glue. Mix by hand and you’ve got something close to the all famous Silly Putty®.
(Source: http://www.statease.com/news/news0212.pdf)
Have fun
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April 25th, 2006
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What do you get when you mix a huge metal spike from home depot, shiny wire from Fry’s Electronics and a 6 volt battery from Radio Shack? Well, today our students found out.
Our lesson for today was all about Magnets, from what they can do, where they come from and why they’re used. David Hicks, a Civil Engineering student from SDSU led the day and gave the students many things to think about.
The students saw a demonstration, interesting pictures of magnets in action, and got a brief bit of magnetic history. Did you know that the first observation of magnetic activity is traced back to a Greek shepherd named Magnes back in 600 B.C.?
The students had to make their own magnets using the materials provided with the freedom to wrap their spike as loose, tight, heavy or light as they wished. Their goal was to pick up as many bolts and screws as possible and figure out how to get the best result.
To produce their magnetic field, the students used alligator clips to connect a 6 volt battery to the ends of the long wire after it had been wrapped.
One student managed to collect 9 bolts and screws on her magnet
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April 24th, 2006
2 cups of pure sugar can easily get you addicted, but for the sake of science our students gladly volunteered their sweet tooth for the experiment.
Today, our students were led by Danielle Ditirro, an SDSU Biology student, through the patterns, formations and chemistry of crystals and how that’s all related to marvelous Rock Candy.
The students started their supernatural solution by heating a half cup of water to about 100 degrees centigrade in a pot (typical boiling point).
Next is the sugar, which is a carbohydrate that’s found naturally in most plants and will dissolve quite easily in water until it reaches its saturation point, which can change with temperature. The students added a little more than 1 cup of sugar into the boiling water and stirred until the solution turned clear and reached a rolling boil.
After the heat was removed, the solution was carefully poured into their small glass jars. They added a paper clip to the end of a piece of string that was previously soaked and dried to help the crystals coat the string’s surface. The paper clip was used to help the string sink to the bottom when it was gently put into the jar leaving, only a short piece outside.
At this point all the students were sticky and moving around the classroom pretty fast. It was tough to convince them to not disturb their experiments for about seven days, especially after they’ve gotten a taste of the nectar.
What will happen is the water will start to evaporate and the solution will then become more and more saturated while the sugar molecules will continue to come out and assemble along the string, eventually growing to a count of over a quadrillion molecules to makes up the irresistible rock candy that we all love to eat.
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April 18th, 2006
That’s right. Higher than 2 Shaquille O’Neal’s. This height is not for the faint of heart but someone has to do it.
Today, the students had the chance to put the final touches on their designs, and bring them out to the Drop Zone.
The excitement was high and the suspense was intense. On the ground, 17 feet below, were screams of glee from the crowd of students hoping to see an egg shatter to pieces and for theirs to survive.
By the end of the day we had 6 students with eggs that did not break. The 6 finalists designed a new space capsule over the weekend to compete in a final break off from approximately 21 feet high. The winners received movie tickets for all their hard work.
Many tried and many failed, but with the proper attention to detail, you too can protect an egg from a 17 & 21 foot drop.
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April 17th, 2006
Today Emir Williams, a Civil Engineering student at SDSU taught our students all about space capsules and why Engineers and Scientists work so hard to make them safe. We used the principles of capsule design as the basis for our lesson and had the students create a space capsule themselves that would hold 1 egg and protect it from breaking when it is dropped.
Each student had a wide variety of materials they could use, with a few limits, and in only 55 minutes the students were able to create some amazingly unique designs.
Some students worked together on ideas, while others worked alone, but in the end each student had their own design ready to go for the next day’s drop.
Competition tends to bring out some of the best work and they could hardly wait for the next day.
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April 17th, 2006
Inspired by a project done at Iowa State University, college students in San Diego took it upon themselves to create a machine that would enable a local kid with disabilities the opportunity to participate in some of the most fundamental activities of schoolyard play. We’re taking about playing catch – which is something that is fun for everyone – for hours without end.
With a very small budget, and a short amount of time, college students created an air cannon that would launch a soft tennis ball over 30 ft within minutes. This original prototype was shown to our middle school students as a way to illustrate impact that engineering has on even the smaller aspects of life.
Over the course of our term we have been exposing our students to a variety of engineering professions and giving them an insight into some of the specific things that each would work on. They know that Engineering is about creativity, discovery, learning and improving on things to enhance our quality of life, and neatest thing of all is that they also know that they too can be a part of the process of making a difference some day.
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March 27th, 2006
After our Science Magic, Danielle Ditirro led the students through the effects of radiation on living organisms.
The students learned what radiation is, where it comes from, its harms, benefits and what it can do to a simple radish seed. After a little background the students had to hypothesize the results of their radish experiment under 3 different conditions; controlled (no radiation), set 1 (some radiation), and set 2 (more radiation).
The students carefully prepared their samples and used the microwave for the assigned amount of radiation they needed. They taped all their samples on a window that got a regular amount of sun and checked back periodically to see what happened.
A week later, Danielle help the students analyze their results and compared that to what they hypothesized. She tallied the overall class results and graphed the outcome. As most of the kids suspected, radiation did have an effect on their seeds.
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March 27th, 2006
Today, Emir Williams, a civil engineering student from SDSU, started the class with a bit of Science Magic by holding water in a glass when held upside down. I am sure that everyone has seen what happens when you put a file card on top of a glass of water and turn it upside down – right. That’s what we thought – and so have all the students. The secret is simply air pressure pushing up holding the card in place.
But what the students did not know is what would happen if we removed the card – do you? We filled a jar with water, put a file card on top, turned it over and the card stayed. Then, while the jar was still upside down, we slowly slid the card away for the jar and … the water stayed in the jar. That’s right, it stayed. The students were amazed.
The secret is surface tension. We cut out a small piece of screen from a regular window, and using the typical jelly jar we replaced the center lid of the cap with the screen and secured it with the screw cap. When the jar was turned upside down, the water molecules between the screen and the file card created a thin layer, or skin, across all the openings of the screen preventing any of the water to gush out until that skin is broken.
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March 14th, 2006
Today, Hayik Malkonian, a Mechanical Engineering student from UCSD, led our students through an activity that involved applied design, force, friction, power, moving parts, and an imagination. Students first learned about the physics behind what they were doing before they got started. The students also learned of the variety of opportunities that mechanical engineers have due to their diverse experiences and educational background.
They learned that these engineers work on more than just cars and they never guessed that a mechanical engineer worked on handheld devices. The students learned about the educational process of a mechanical engineer and what they can expect to get paid with their degree.
This 3-day activity had the students design and build a cardboard racer that used a motor, a 3 to 6 volt power supply, and polarity switches. Their racers had to go forward, reverse and stop on command and work long enough to win the race. Each student had to position their motor properly on the axial and they had to wire their own electrical system for the car which had an extended switch box with a double throw, and double pole switch to control its motions.
In the end, it came down to 2 students and team Stevan & Francisco beat out team Crystal. The winners received a gift certificate to Rubio’s.
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March 13th, 2006
Creative circuits is what we called it, but its nothing more then a dexterity game that could keep you going for hours. Do you remember the old Hassbro© game called operation? Well, that’s the concept we use to recreate a classic.
Today, the students were led by Emir Williams, a Civil Engineering student from SDSU, through an introduction into electrical conductivity and wiring. The students learned about electrical engineers and the huge variety of things they work on. They learned about their educational paths and what places look for electrical engineers. Right before the activity started they also learned about power, conductors, a load (such as a light bulb or motor), circuits, current paths, the difference between AC and DC, and connecting batteries in series to increase the voltage.
The class used wood, bolts, screws, various lengths of wire, lights, a loud buzzer and a firm piece of metal. Each student had to connect their power supply to the system so that current will only travel through when the game’s wand touched the wire, ultimately completing the circuit.
The students had a great time and created some uniquely weird designs that were almost impossible to navigate through. With the light flashing and the loud buzzer sounding every time the wand touches the wire – I hope the parents let them come back next week.
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March 6th, 2006
Today, our students got a short 2000 year old history lesson on the concept of trajectory, mechanics and physics as the Greeks and Romans used to create their throwing machines.
Emir Williams, a Civil Engineering student from SDSU, led the students through a 3 day activity that ended in a water balloon war.
During lecture the students learned about the effectiveness of different types of catapults, the materials used, and their origins. They discussed the concepts of Kinetic and Potential energy and ways they are produced. They also discussed measurements and basic drafting so that each team would be able to take the proper measurements, and effectively sketch out the design ideas from 3 different views (top, front, and side).
The students used PVC pipes, connector joints and their choice of bungee or springs. After drafting their design, they collected their materials and got to work cutting their pipes to length and assembling the catapults.
The kids were really having fun because their imaginations went wild on the distance their projectile would travel.
On the day of the launching event we all set up, and had them launch their solid projectile one–by-one. We measured the distances, and one team managed to launch over 20-feet. At the end, we brought out our secret water balloon projectiles and the war was on. Good thing the sun was out that day otherwise we all would have caught a cold.
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