The theme for this week’s Unplugged Project was fast. This is a fast post because the week went really fast, and we will soon be flying in a fast airplane to France.
We did experiment with some rubber band powered cars, and finally succeeded in making an original prototype from a Knex Set that went very fast…for about 6 inches. I think the axle needs work, as does the length of the rubber band. It was fun, even though our model obviously needs improvements.
If you have budding engineers at your house, try this project and see what you can come up with!
If you did a fast-themed Unplugged Project this week then please link to your post below (not just your blog, we always want to be able to find your fast post). If you didn’t do a fast project, then don’t link, but please read more about how to join in the Unplugged Project here. We’d love to have you!
++++++++++
Since I will be away until August 6th, the Unplugged Project will be on vacation also (although, if anyone is interested, I hope to post a few virtual postcards from France, perhaps even one a day if I can!).
The next Unplugged Project will be Monday August 10th and the theme will be:
Photograph
I bet we’ll have a lot of photos by the time we get home, and you’ll have a lot of time to think about what you will do with your photos!
The theme for this week’s Unplugged Project was powder. I’ll admit that this particular choice was somewhat premeditated since I thought a baking soda project would be fun. Baking soda is a powder, right?
Fondly remembering a baking soda boat that came in a cereal box once when I was a child, I suggested we try and make one. My children were enthusiastic but leery, remembering a particularly violent baking soda volcano we made one time!
I am sure they were rolling their eyes and thinking:
“Oh no, here goes Mom with the baking soda again.”
Is that what they’ll remember about me as adults?
“I don’t remember much about Mom, but she did like playing with baking soda and vinegar.”
I found instructions here on the PBS Zoom website for a boat made out of a plastic bottle. Never being able to simply do what instructions say, I had to experiment, so we tried a sippy cup boat too!
We needed baking soda, vinegar, and our bottle and cup.
Using a hammer and nail, we made a hole in the cap of the bottle. The hole is the exhaust pipe through which the carbon dioxide gas escapes propelling the “boat” through the water.
The sippy cup already had holes of course, but I covered up the vent hole with some masking tape so the only vents would be in the spout.
Supplies in hand, we eagerly headed off to the bathroom and put some water in the bathtub.
The Zoom website suggested wrapping the baking soda in toilet paper to slow the reaction. Remembering my volcano, I thought this might be wise advice.
We poured baking soda onto a strip of toilet paper:
And rolled it up:
We tried the sippy cup first and poured in some vinegar.
Next we put in a few marbles to weigh down the spout (where the “exhaust holes” are), so it would be underwater. Coins work too. It is important that the exhaust holes be under the water line so there will be more resistance (of the water) to propel the boat.
The kids cringed when I dropped in the toilet paper package containing the baking soda.
I quickly put the cap on and placed the cup in the tub. The cup whizzed around the tub accompanied by many oohs and aahs.
The toilet paper worked nicely to delay the reaction giving me time to put the top on, but on the second attempt the toilet paper clogged the exhaust hole stopping the “boat.”
We tried the bottle too. Same procedure: vinegar, toilet paper/baking soda and marbles. The bottle sailed around the tub.
Since we were having clogging problems with the toilet paper, we also got brave and dumped the baking soda in, poured in some vinegar and tried to get the top on quickly. Unfortunately we were never able to be quick enough, and those boats didn’t work as well since, as you can see here, a large part of the chemical reaction occurred before the top was on.
In light of my baking soda and vinegar obsession, this could become quite a project: how to control the reaction without clogging, what sized hole produces the best results, what proportions of baking soda and vinegar generate the most power. Nerd heaven! Look out for a blog post one day with my perfected version of this project.
My kids went on to create their own experiment with baking soda and vinegar in a plastic wipe box:
Fortunately we ran out of baking soda before they were able to blow the box open!
Did you join us this week for a powderUnplugged Project? If so, please link to your powder project post (not your blog) below. If you didn’t join in, then please don’t link but read more about how it all works here. We’d love to have you!
Oh, I had better get this up now before Turnoff Week starts tomorrow and we are all supposed to try not to be on the computer!
The theme for this week’s Unplugged Project was science. I actually have something to post about science, but I didn’t get to it today. Perhaps I will post tomorrow, but I’ll try and post quickly!! I’ll link to it in Mr. Linky below if I get to it.
If you have a scienceUnplugged Project to post, please link to your project post in Mr. Linky below. If you didn’t do a science project, but want to join in in the future, please read more about the Unplugged Project here. We’d love to have you!
PS: It’s not too late to join in the Turnoff Week Blog Challenge for a chance to win a $10 Amazon gift certificate (Turnoff Week is April 20 - 26). Read here for more information!
The theme for this week’s Unplugged Project was ball. My original thought was golf ball. We live on a golf course so our backyard provides us with a constant supply of golf balls!
We are still feeling very “sciency,” so I decided to stick with a science project like last week. For a while now, I have been wanting to try a trick that I have seen on a larger scale at a science museum: “floating” a ball in a stream of air to demonstrate Bernoulli’s Principle.
As a pilot and a flight instructor, I am very eager for my children to understand the physics of flight. I have given them many lessons on the shape of airplane wings. Each time we go someplace in our plane, I ask them to tell me about how the shape of the wing creates the lift that makes the plane fly. In fact they have heard me go on about it so many times that they are now at the eye rolling, “here goes Mom again” stage.
I thought that they would enjoy this “magic trick” and felt they were ready for it as an added lesson relating to the airplane.
All you need is a hair dryer and a ping pong ball. We had no ping pong ball (and golf balls are too heavy to use with the hairdryer) but I found a lightweight plastic ball in the playroom. It was larger than a ping pong ball, but weighed about the same.
Turn the hair dryer on to high (if you have a “cool” setting, that’ll save your fingers from burning as you play with the ball) and point it straight up toward the ceiling. Place the ball in the air flow. If your ball is light enough, it should hover there.
You can slowly and gently tilt the hair dryer sideways and the ball will “follow,” remaining in the air stream until the angle is such that the force of gravity is stronger than the “lift” generated. The ball will then fall to the ground.
For more fun, use a shop vac and some heavier balls. (I recommend that you do this outside!) Remove the hose from the vacuum port and attach it to the exhaust opening. It will now blow air instead of suck it in. Golf balls will work. Try the lightweight ping pong ball that you used with the dryer too and you’ll see that with the stronger airflow, it will balance much higher.
Why do balls “float” this way? Because of Bernoulli’s Principle! Bernoulli’s Principle basically says that the faster a fluid (or air) flows, the less pressure it exerts.
To understand this experiment, you also need to know that air flowing over a curved surface flows faster than air flowing over a straight surface (the reason for this is complicated, but has to do with the same mass of air being forced through a smaller area - the curve takes up more space than the straight edge).
So: The air that flows over the curved surface of the ball must flow faster than the air that goes straight up around the ball without touching it. The faster flowing air in contact with the ball exerts less pressure than the surrounding air that is traveling straight up. The lower pressure ball is “trapped” inside a cylinder of higher pressure and is thus held in place.
How does this relate to airplanes? An airplane wing is curved on the top, and fairly flat on the bottom, as you can see in this drawing:
The air flowing over the upper curved surface flows faster than the air flowing along the lower, straighter surface. This means that the pressure on the top of the wing is less than that below the wing. Thus the wing is “lifted” or sucked upwards.
Airflow over a wing:
After the fun of last week’s video science lesson, we made another one this week. It is a bit longer (nearly 3 minutes), but we hope you enjoy it!
++++++++++
If you did a ballUnplugged Project this week, then please link to your project itself (rather than just your blog) in the Mr. Linky below. If you didn’t join us, but would like to find out more about it, please don’t link, but read more here.
Thanks to a suggestion from Meg at Bare Baby Feet, this week’s Unplugged Project theme is balance. We felt “sciency” this week, so my oldest daughter and I scoured our favorite science book but found nothing that sounded fun to her.
I did a few Google searches and happened across this amazing-seeming experiment. I tried it and then showed it to my children who were very impressed. As you will see, I tried to make it even more fun for kids by modifying it to make a balance toy: a flying bird. Read on for more!
THE SCIENCE:
This experiment (which I understand is often shown as a magic trick), involves two identical sharp forks, a real cork (a real one is a bit softer and easier to use than a plastic one), a toothpick, and a glass. Push the forks into the sides of the cork.
They should be in the middle of the cork, directly opposite each other. The cork will not be in alignment with the forks. Try to have the forks at a 90 degree angle to each other, like this:
Push a toothpick into the end of the cork, on the side between the forks (be careful, the toothpick breaks easily, so be gentle). You will have something like this:
Experiment by balancing the toothpick on your finger. It seems impossible, but once you find the right spot, the forks will just balance. You can mark that spot on the toothpick with a marker, or just remember about where it was.
Place the balance point of the toothpick on the edge of a glass. The forks should remain suspended on the side of the glass. Pretty amazing!
Now, for the grand and very dramatic finale! Take a match and light the end of the toothpick on fire (yes, I really did say to set fire to the toothpick - YOU, not your kids of course :-) ). The flame will move up the toothpick, burning it into nothingness. The fire will stop when it reaches the rim of the glass.
Does the cork fall down? NO! It stays put, hanging by practically nothing on the rim of the glass. You can even lift it off and place it back on, barely touching the rim, and the whole thing will balance.
Here’s a video I made of the toothpick burning (I have never put a homemade video on my blog before so I really hope it works). Watch closely and you’ll see that my son tried to knock the whole thing off the glass at the end of the video but it just bobbed up and down and returned to its original position. Very stable!
How does this seemingly magical “trick” work? Warning: science stuff coming up - feel free to skip to the next section if this is all “blah blah blah” to you.
But the center of gravity does not necessarily have to be on the object itself. Here it is actually in the open space between the forks. This means that, unlike a see-saw, the object is not balancing on its center of gravity (“CG”). Instead it is balanced on a separate pivot point (the toothpick on the edge of the glass) away from the center of gravity.
We had to arrange the forks so that their mass was a bit lower than the center line of the cork in order to insure that the CG remained lower than the pivot point. Since the CG is lower, if the fork assembly is displaced, the CG will be raised and gravity will pull it back to equilibrium. You can see this in my video. All balance toys have a CG that is below their pivot point. (NOTE: I am NOT a scientist! Any physicists out there may disagree with my terminology, etc., but I am trying to make this as simple an explanation as possible.)
THE FLYING BIRD:
Not wanting to use my good forks as permanent bird wings, I had to think of something else. A matching pair of thrift store forks would have been ideal, but the thrift stores were all closed today. I ended up using a set of small screwdrivers that came from the bargain bin at the local hardware store, and that turned out to be not what my husband expected. There were four screw drivers, so by using two corks, my daughter and I were each able to make a bird.
We stuck them into the sides of the cork at the appropriate angles (see above). They were actually easier to get in there than the forks were.
TIP: Test “fly” your configuration on a glass before proceeding further. Adjust the screwdrivers (or forks) now if necessary to get it right. I didn’t check mine before-hand and had to fiddle later after the feathers were on.
To create a good surface for sticking on feathers, I cut construction paper into a symmetrical wing shape. By folding the paper and cutting double thickness (while keeping a portion of the fold intact) this was easy:
We then covered each screwdriver with a paper wing and stapled it so that the screwdriver was hidden inside. Staple as close to the screwdriver as you can so the wings stay on. It doesn’t matter if the staples are in the middle of the paper because you are going to completely cover the paper with feathers.
Paint your cork if you want to.
Next, glue on feathers. We had “natural-looking” feathers and “fake-looking” feathers, both from Walmart a long time ago. I opted for a colorful, fake bird. My daughter chose to be more natural. Elmer’s white glue didn’t work so well, so I broke out the hot glue gun and we began sticking on feathers.
I found an old jar to be a useful stand for our sticky birds while they dried, as well as for painting the underside of the cork.
After things have dried a bit, you’ll need eyes (googly or beads) and a beak of some sort. We cut the tips off some new crayons with scissors to make our beaks and they made perfect beaks! Glue them on with the glue gun.
If you haven’t already, carefully stick a toothpick in the back end of the bird.
Once everything is well dry, you can “fly” your birds on the edge of a glass. If properly balanced, they’ll bob up and down when touched, but won’t fall off. PLEASE don’t try the flame trick since you don’t want to risk setting all the glue and feathers on fire!
++++++++++
If you did a balance project this week, then please link to your project post in Mr. Linky below. I really prefer links to project posts rather than blogs in general, so that readers will always be able to find your project no matter how far down it is buried in your blog. If you did not do a balance project, please do not link. Read more about how to participate here. We’d love to have you join us!
I am "Mom Unplugged," Montessori teacher and mother of three children ages 11, 9, and 6. I invite you to read more about me and my blog here. Thanks for stopping by!
Comments (4) 
but found nothing that sounded fun to her.
Themocracy