Dana Edwards’ Blog

It has been a few months since Brennan and I did a science project.  This has been the case mostly because of his fascination with trains, specifically traction rods on trains. I am thinking that the trains fascination may run its course pretty soon but hopefully not before we take him on his birthday party which is all about trains. Enough on trains for now … I’ll post birthday pictures soon.

An upcoming fascination of Brennan’s is Tornados, which I agree are really cool to look at but not too cool in real life for those that are unfortunate to be in one.  He has memorized the Fujita scale but hasnt quite latched on to the concept that the size of tornado doesnt dictate the strength of the wind.  That’ll be a next step. Here is a quick video of it in action:

To make a long design / science discussion short, the box is cut so that there are slits in the sides which make the tornado funnel spin as a motor on top sucks the dry ice smoke up. Email me at dana@danaedwards.com if youwant to know more about the physics of how it works. Here are a couple of photos of it in action:

We had a blast making it and hope to show it off to the grandparents for Spaghetti Night tonight and Thanksgiving Dinner soon!

- Dana

Well, this past weekend (January 24-25), we went to visit my brother-in-law, Patrick, who is headed to Iraq. On the way there, I sketched out an improbably catapult, which we built and fired a couple of times.  It was powerful yet a bit unsatisfactory.  It used a bungy cord for the power and had a firing arm about 2 feet long.  While we were building the trebuchet, Brennan snuck over and fired the catapult himself:

The nice thing about the catapult (Falcon 4) is that we made it completely out of scraps and recycled material.  The bad thing is that only fired a gumball about 10-15 feet.  If you decide to build one, please make sure that you don’t leave your kids alone around them as they definitely have some snap-back. That said, we challenged ourselves to something bigger … and Falcon 5 was born.

We spent a few minutes on the Internet and found some substandard free plans for miniature seige weapons and were unsatisfied so we sat down and drew this one out.  Luckily, it worked only after about two or three modifications to the original design.

The first step was to build the frame – a 54″ by 27″ box made out of 2″x4″ lumber. As you can see, it is also the perfect size for Brennan to lay down in.

You can see in the picture that there is a cross lap joint which is about 3.5″ wide to fit and hold the uprights.  This was a pretty cool experience to see Brennan working with tools really for the first time mostly by himself. I was impressed to see him using a hammer that was about as big as he was.  And don’t worry he didn’t operate the chop saw in the photo.

After chiseling the joint and cutting a half lap in the uprights, we attached the 40 in uprights with drywall screws.  For a crossbar, we bought a steel rod from Home Depot and cut it to fit the width.  For the swing arm, we cut a 8 ft 2 by 2 down to 6ft.  The cross bar split the swing arm at about 41 inches.

Instead of creating a trough specific for the projectile to slide down, we just put a piece of plywood to the cover the entire surface of the frame.  For the counterweight, we used a 10lb diving belt weight and the pouch which was cut from a shop towel was attached to the swing arm with twine.  This was definitely a pretty simple trebuchet to build but then again, we did it with no plans and no help.  At the end of the day, we were able to consistently launch a 0.1 lb ball of kidney beans wrapped in aluminum foil about 35-40 ft.

Here it is all finished and being fired for the first time.  If you look to the left of the swing arm in the second picture, you’ll see the first gumball we launched and the first pouch which we made out of duct tape (it didn’t work well at all).

I’ll post a video now that I am back in Charlotte and have my video camera. I have to reassemble the trebuchet when Jill isn’t looking so wish me luck.

Dana

Brennan has enrolled in swimming classes now and is showing some interest in it – woo hoo! Being a former competition swimmer, I hope he continues but up to this point, he is pretty scared of the water.  I guess I understand for now.  While I dont know for sure, I started thinking that he was scared of sinking in the water and not coming back up.

So last night, I started trying to explain to him why he would usually float and what it takes to sink. I found an old book in our home library called Floating and Sinking. Unlike I hope you find this blog, it was very confusingly written but it did serve its purpose of putting him to sleep.  The whole time he asked many questions as to how floating and sinking worked. The easiest way to explain it for me was to say, “Things float when they are less dense than whatever they are in.” That triggered a whole discussion on density. As you have probably figured out, I think people learn best by doing – hence, this post on The Sinking Straw.

This takes about 5-10 minutes to build and is quite easy.  Here is what you need:

In case the images didn’t come up:

• 1 small rubber band
• 1 straw cut to about 4 in long
• several small paper clips (mine needed 4 but it varies)
• 1 2l bottle – like everything we do
• 1 “test vessel” which about the same height as a 2l bottle

Instructions:

1. About an inch down, wrap the half of the rubber band around the end of the straw
2. Fold the end of the straw down and wrap the rest of the rubber band around it
3. Put several small paper clips in the other end of the straw. After testing, I found I needed four. You may need more or less.



4. Now, test your straw sinker in the test vessel which is filled with water.  Drop it in and push down on the top of the sinker. If it barely floats and comes back up when you tap it – congratulations you inserted the right amount of paper clips.



5. Fill the 2L bottle with water almost to the top.
6. Drop in the sinker
7. Screw the cap on very tightly so water doesn’t spray everywhere.



8. When you squeeze the bottle, the sinker should drop.  When you let of the pressure, the sinker should go back to the top. It’s a gift that keeps on giving with every squeeze!

Why does this work?

Magic of course.  Or … Squeezing the bottle reduces the amount of space that the air can take but the water takes up the same amount of space so some water goes up in the straw.  The water in the straw makes it heavier. Since the straw’s volume didnt change it is more dense and so it sinks.

Brennan’s video play by play:

Dana

The Falcon series continues. After Falcon 1, Brennan and I decided to build more projects every couple of weeks and they would follow the the crafty naming convention Falcon 1, Falcon 2, Falcon 3, etc. Well, here we are at Falcon 3. What happened to Falcon 2? It was a failed attempt at making a boat in response to needing to beef up home defense per @cp2 “@danaedwards need it for defense when we get to 25% unemployment”. I guess that was part of the motivation and the other part is that it was just fun and I got to explain how it worked to Brennan who has not stopped playing with it since we finished.

Building this took about 30 minutes, 9 popsicle sticks, a pair of scissors (or utility knife), a roll of tape, a rubber band, a pen and a ruler.

I’ll post the steps to build a little later as they are intricate.  Here was Brennan’s video of the second firing of it:

-Dana

Wow! I never thought a toy that looked as cool as this would be this bad. The Magnext Dynamix Gears and Elektronix is clearly the worst toy I have seen this year. The toy was billed as “helps understand the basics of physics in an innovative, fun and cool way” so I was drawn in fast. My son loves gears, rockets (see Falcon 1 post), electricity, magnets and pretty much anything that moves if you press a button. This was going to be the toy for him. I would find out after about 15 minutes that the other marketing line was slightly more accurate “Encourages patience, observation and a great sense of accomplishment”.  It definitely encouraged patience but I had none for this toy.

Here were the issues:

• the gears didn’t snap easily onto the base
• when the gears would snap onto the base, they hardly ever turned without a push
• when they did turn, they were quite uninteresting unlike the photo on the box
• no instructions were included in the box to help figure out how to make the “20 interesting designs”
• my son quickly lost interest in it

I think the best way to describe this is a technical toy that a product designer probably worked very hard on building but it’s terrible.  The toy was so bad that if I were the company, I would let the designer go.

Dana

So, I need to repost the Falcon 1 Maiden Voyage as it has been enhanced by carlparziale (cp2 on twitter & founder of OCV Facts site). His addition to the video has greatly increased its value:

Here is the original:

Make sure you watch them and leave comments!

Dana

Brennan and I completed our first science project of the year – Falcon 1.  This one demonstrated Newton’s Third Law which says every action has an equal and opposite reaction. I think he understood a little bit because he said that as I filled it up, the air went in which force the water out and the bottle to fly. This is close enough for a 5 year old.

It took us about 30 minutes to make and takes very few things:

• a champagne cork – clearly we had one since it is 1/1/09
• serrated blade
• a 2L coke bottle
• transparent duct tape
• a valve stem
• Bicycle Foot Pump

If you have all of that, you’re set.  You can find the corks, serrated blade and duct tape at Lowe’s.  I went down to the local tire store and asked for the valve stems – the store gave them to me for free.

Instructions:

1. Remove the label from the coke bottle
2. Wrap the bottle with duct tape to reinforce the bottle in case of nicks / scrapes
3. Write something really cool on the tape with a Sharpie – perhaps “In honor of Falcon 1″
4. Cut off the bottle top ring with the serrated blade.
5. Trim the head of the champagne cork
6. Test the cork to make it sure it is close to fitting. This will be trimmed later.
7. Drill a hole which is slightly smaller than your valve stem to fit the style of valve stem you have.
8. Test that the valve stem fits into you hole.
9. At this point putting the valve stem into the hole has expanded the size of the cork.  You will need to test / trim the cork until it fits.  Be careful not to cut off too much or you will need to drink another bottle of champagne – or darn.
10. Once it fits in the bottle, take it out and fill the bottle 1/3 full with water.
11. Assemble a launch pad out of whatever you have. I used a bag of fertilizer and some paint cans. Ha!
12. Attach the bike pump to valve stem.
13. Pump up the bottle and watch it fly after about five pumps or so.

I have save the maiden voyages of Falcon 1 on YouTube.com – Falcon 1.

Enjoy!

Dana