Pumpkin Time!

Sun, 28 Oct 2007, 19:24

It's almost Halloween! We already had one pumpkin picked out. But our daughter brought home another one from her visit to Black Creek Pioneer Village. So we had two pumpkins to carve this time. The one on the left is her design.

photo of pumpkins

Hans

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the city
 

Butterfly

Category: Stained Glass
Thu, 25 Oct 2007, 09:52

I didn't get a lot done last week since I got hit with that cold that's running around. But I did finish my first stained glass project, a simple butterfly.

picture of stained glass butterfly

Hans

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The Rotating Paper Cylinder

Category: Science
Thu, 18 Oct 2007, 20:51

I first tried this more than three decades ago after reading about it in Martin Gardner's monthly column in Scientific American. It was a fun trick, and at the time, it almost convinced me that I had psychic powers.

To do this "experiment", make a cylinder out of a piece of paper as shown in the following photo. Before you glue the ends together, you may decorate the cylinder as you please. Support the cylinder with another narrow piece of paper pushed through slits on opposite sides of the cylinder, and balance it on a suitable narrow support with a pin or needle. The cylinder should rotate freely. If necessary, adjust the cylinder so that it rests more or less vertically.

Cylinder

With the cylinder balanced and still, carefully cup your hands around the cylinder without touching it, as shown by the following photo:

Cylinder

Concentrate on the cylinder. After a few seconds, the cylinder should start to rotate. Before I offer the explanation for this behavior, think about why this happens.

One possible explanation is telekinesis, the ability to initiate movement without perceptible mechanical means, merely using the power of ones mind. Think of ways to test this hypothesis. Is it even possible to test this hypothesis? Note that if the theory is not testable, it is not, by definition, a scientific theory.

The real reason for the rotation of the cylinder is quite mundane. The cylinder is quite vulnerable to the slightest air currents. By cupping your hands around the cylinder, you are magnifying the slightest currents, increasing the chances that the cylinder will be affected by these currents. Your own breath may itself contribute to the "breeze" surrounding the cylinder.

A clever sort of person, though, could easily convince gullible spectators that his psychic powers moved the cylinder.

I'll leave you with a chemistry joke I heard recently at the Ontario Science Centre. Two atoms are chatting:

First atom: "I just lost an electron."

Second atom: "Are you sure?"

First atom: "Yes, I'm positive!"

Hans

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the four elements
 

Introduction

Category: Stained Glass
Thu, 11 Oct 2007, 14:11

For a while, I've been interested in stained glass as a creative hobby, but was always intimidated by the skills needed. But this year, Sylvana signed me up for a course, and so now I'm taking the plunge. This section of my blog is intended to document my efforts in learning about stained glass. I plan to write about the tips I learn, as well as current projects.

My class meets once a week at the Cedar Ridge Creative Centre in Scarborough. At first, there were seven students, but three got turned off by the cost involved and dropped out immediately. Cost is certainly an issue since you need a number of tools specific to the craft. These include a soldering iron and a glass cutter. A grinder is also needed and is the most expensive of all the tools, but before making that commitment, we can use the grinder at Cedar Ridge.

Courses are also available at the local stained glass store, Glass Images, which provides a 10% discount to anyone taking a course in stained glass, including courses held elsewhere. When I bought my tools and supplies there, the sales person was very helpful, and answered all my questions. She even filled my glass cutter with oil, and engraved my cutter with my initials!

At this weeks class, we practised cutting glass. Personally, I expected this to be the most difficult aspect of the craft, but I had little trouble, even with breaking apart pieces of glass with my hands. We started with clear window glass, which easily broke apart cleanly. It takes a bit of a knack, though. The action needed is a combination of flexing the glass and pulling it apart. Cutting colored glass was a little bit more difficult, but still not as bad as I had first expected. During the class, I don't think I made any mistakes, even with more difficult inside curves.

Next week we get to foiling and soldering the glass pieces. I decided to start with an easy project, a butterfly consisting of five pieces of glass. I'll post a photo when I'm done. Later, I hope to try my hand at three-dimensional pieces.

Hans

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glass
 

The Bottle Diver

Category: Science
Wed, 03 Oct 2007, 12:00

Here's a fun and easy science demonstration you can use to amuse your kids that needs just a two liter plastic pop bottle and a medicine dropper.

First, fill a tall glass with water and drop the empty medicine dropper into it. The eye dropper should float in the water. Next, completely fill the medicine dropper with water. It should now sink in the water. Now, carefully squeeze water out of the dropper until it just floats in the water. Then, squeeze out a couple more drops out of the dropper.

Now, fill the two liter pop bottle with water right up to the top and put the medicine dropper into it. A bit of water should spill out the top of the bottle. Put the cap back on the bottle and tighten it closed. You're now ready for the demonstration.

At first, the medicine dropper should float at the top of the bottle. But when you squeeze the bottle, the medicine dropper should sink. With the right amount of force, you can adjust the depth of the "diver" within the bottle.

Before reading on, try to reason out why this works.

Diver Diver

Ready for the answer? When adjusting the amount of water in the medicine dropper, think about when it sank or floated. With a lot of water, the dropper sank, but with little water, it floated. To put it differently, with little air in the bulb, it sank. Containing a lot of air, it was buoyant and floated.

What happens when you squeeze the bottle? Do you compress the water? Or do you compress the air in the medicine dropper? With a smaller volume of air in the dropper, it becomes less buoyant and sinks.

With this story, I open a new section of my blog devoted to science.

Hans

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the four elements