Not-So Shocking Chemistry

Today, we're going to find a way to shock (maybe) your friends.

What we're making today - a wet cell battery. 
Wet cells were used before batteries as we know it now were invented.

List of Supplies:

• Lemon juice (fresh lemons or a bottle of lemon juice OK)
• Paper towels (cut into small pieces. Not too much bigger than the coins)
• Bowls (one small and one big enough to hold the juicer)
• Coins (equal number of nickels and pennies). I used 15 coins each.
• Multimeter*
• Lemon/citrus juicer (optional)

Cut the lemon in half and squeeze the juice into a small bowl.

Soak the pieces of paper towel in the lemon juice.

Begin to stack coins, starting with a penny and alternate between nickels and pennies.

Measure the voltage between the coins (2 sets of pennies and nickels). 

The multimeter reads 190 micro volts. 

Try to measure the voltage readings. 4, 8, 12 and 15 sets of coins 

or 3, 6, 9, 12 and 15 sets of coins.

This is one of the reading for 15 sets of pennies and nickels.

My voltage readings were as follows:

• 4 sets of coins, 190 micro volts
• 8 sets of coins, 206 micro volts
• 12 sets of coins, 303 micro volts
• 15 sets of coins, 530 micro volts

I noticed that the longer I hold the leads to my coin battery, the higher the voltage readings. I had 12 set of coins read higher than 530 micro volts when I held the leads against the coins for over 45 seconds. The above readings were what I got within 10 seconds of holding the leads to the coin battery.

Theoretically, when you touch the ends of your coin stack with your fingers, you should feel a mild shock, but I didn't feel anything. Maybe I did something differently? Maybe you'll feel something. I don't know.

Science Notes:

•  The two types of coins have different electrical charges in their atoms.

1. Nickel (anode) is electron rich, which means it's negatively charged.
2. Copper (cathode) is electron poor, which means it's positively charged. 
3. The electrons will flow from Nickel to Copper coins and create an electric circuit.

• Lemon juice, which is a weak acid, conducts an electric current between the two different coins.
• By stacking coins on top of one another, we’re increasing the electric voltage of our wet cell battery. So, this explains why when we have 15 sets of coins should give us the highest voltage reading.

Notes on multimeter:

You can purchase one from Harbor Freight for $5.99, but if you have one of their coupons, you can get it for Free. If you don't have a Harbor Freight nearby, you can purchase one from Home Depot for less than $10.00 (I've seen it as low as $6.99).

Mess factor:

It really wasn't too messy. Basically, confined to a tray and a bigger bowl.

I hope you have a great day.

Hoop Gliders

I came across these hoop gliders several years ago, but I revisited them with my children when we were participating in the Tech Challenge 2016, Taking Flight. And just like the Birds of PLAY, we made these gliders to prototype (we thought using the gliders in the shape of birds would be fun at the competition) and understand the mechanics of flight.

Before you start, throw a plain straw. Does it fly well? Not really. It’s because the straw doesn’t have wings. It has nothing to generate lift. But when you add hoops, they act as wings, generating lift. And depending on where you put the hoops, your hoop glider will generate more lift or less. You experiment with sizes and locations of the hoops and decide what works best for your hoop glider. 

 This is what we're making today. 

These are quite simple to make, and they are incredibly fun to throw and watch them fly. This is a great project you can do with your children/students inexpensively. I hope you try this project and have a lot of fun.

List of Supplies:

·                     Straws (different lengths and diameters)

·                     Paper strips (copy paper, construction paper, cardstock, etc., whatever you have handy)

·                     Scissors

·                     Adhesive tape

Cut the paper in 1/2" or 3/4" strips. You can experiment with other widths, but these are the widths that seemed to work best. I also have three different sizes of straws. For my convenience, I made my hoop gliders with the wider, pearl drink straws. But I had students make hoop gliders with regular straws, and they did well with the smaller diameters, too. So, it really doesn't matter too much. Again, if you have different sizes available, experiment.

These paper strips are 3/4" wide. I like this width for no other reason than that it's the width of scotch tape. So, that's the width I use, but I've seen other project instructions online with 1/2" width instructions. Tape the ends of the strips together and make circles. You can experiment with lengths, but I tend to use 3", 6", 9" and 12" strips. I don't know why. I think it's the proportions that matter, not the actual lengths.

You can put as many or as few hoops as you want. But the minimum number is 2.

Have fun with where you put the hoops. Go crazy and fail spectacularly!

As you see, the left hoop gliders hoops are not aligned. The hoop in the back is attached in the middle, but the hoop in the front is attached to the right handside. Play with where you attach the hoops - in the middle, left side, right side, etc.

Just want to show you the different sizes of the hoops I attached. Again, the goal of these projects is to have fun.

I made 4 hoop gliders this morning. but when I conducted this project in class, some students have made as many as 10+ gliders. So, make a lot and have fun.

How to throw a hoop glider. Gently throw it forward.

 

This one flew pretty straight and far.

This one flew the farthest, almost toward the fence & the rose bushes.

This one was interesting to look at slow-mo, because the largest loop would swing back and forth between left and right. But it didn't fly far.

This one was all over the place, but interesting to watch.

It's a perfect day to fly gliders! Have fun!

Birds of PLAY

This was in the Make magazine a couple of years ago, and when we were participating in the Tech Challenge 2016, Taking Flight, we made these gliders to prototype (we thought using the gliders in the shape of birds would be fun at the competition) and understand the mechanics of flight.

I don’t quite remember what the instructions were except that we drew gliders in the shape of birds on a foam plate and experimented with different combination of shapes in gliders and tails.

This is a great project you can do with your children/students inexpensively. I hope you try this project and have a lot of fun.

List of Supplies:

• Foam plates
• Paper clips
• Scissors
• Adhesive tape (optional)
• Pens or Pencils

Build Instructions:

There is no perfect shape to start off. Experiment with the size and width of wings to find your best design.

As you can see, I have four different shapes and five different tails. The gliders are identified with letters in the back, just like the tails are identified with numbers.

The gliders are "lettered" to find the best combination of shapes and tails.

Gliders are assembled. Ready for flight testing.

I put aielerons on this right, bottom glider to see if they made any difference, but they didn't. In fact, it didn't fly as well as the one above it (which is basically the same glider design except for the aielerons)

Again, with 4 different shapes and 5 different tails, you can have a lot of fun flying them and figuring out which combination works the best. 

In these videos below, I've recorded two different combinations which flew the best. Enjoy & have fun!

Video 1

Glider B, Tail 2 combination

Video 2

Glider D, Tail 5 combination

Find your own best combination and have fun with Birds of PLAY!

Hint: DON'T try to throw these. Just hold them by the tail area (without skewing the tail position), and let go gently.