## Friday, August 17, 2012

### "The Browser" show on KSL Newsradio

Our Cheeto Summer blog was featured today on KSL NewsRadio's show The Browser today. They have posted some posted photos of their experiments on Facebook

They featured our Cheeto Helmet and Cheeto Sound Dampener experiments. They didn't focus much on the science of the experiments, just on the fun of doing them. The kids were thrilled to hear their names on the radio. It was a grand end to our Cheeto Summer break.

You can listen to the podcast here. The segments starts at 18:30.

## Friday, August 10, 2012

### Build A Rocket Launcher For \$20

Recently I was reviewing with a friend the modifications our family had made to the rocket launcher described in the Cheeto Cannonballs post. He asked how much it would cost for him to build a launcher. I thought that with some simplifications to the design I could probably build one for \$20. This post is to document how to build a compressed air rocket launcher for \$20.

Simplifications

I have learned a few things from the previous launchers I have built. First, the air reservoirs don't have to be very big. It doesn't take much air to push the rockets. Larger chambers take more work to fill, which is an issue if you are using a bike pump for pressure. A smaller reservoir also means less cost in materials.

Another simplification is to use the fewest number of parts. Some launcher designs have two reservoirs. The second tank looks cool but adds no functional value. Other designs have lots of pieces to reduce the diameter of the pipes. Each piece adds extra cost.

Also, I tried to use threaded connections whenever possible. Having threaded parts makes it easier to change the launcher afterwards (or fix mistakes).

Finally, many designs require legs or a stand for the launcher. This makes storage harder and requires more time to build and more money to buy the additional pieces. My launcher is in a U shape so no stand or legs are necessary.

Construction

Home Depot had pre-cut 2 foot sections of PVC pipe. I used a 1.25 inch pipe for the reservoir and a .5 inch pipe for the launch tube. I chose the cheapest automated valve I could find that had .75 inch couplings. Those three main parts form a U shape, with diameter reducing elbows between them.

Here are the parts I purchased.

Here are all of the parts laid out how they will be assembled.

The first step was to drill a 1/4 inch hole into the end cap and we screwed the air connector piece directly into the cap. (Our launcher will be connected to a compressor. A valve stem could be place here if using a bike pump to compress the air.) Then we glued the fiew pieces together that weren't threaded.

Finally, we threaded in the sprinkler valve, covering the threads with teflon tape. An embossed arrow on the side of the valve indicates the direction the air should flow. The valve won't work if inserted backwards.

At this point we had a functional launcher for less than \$20. All we had to do was touch the leads of the sprinkler value to a 9 volt battery and it worked. This is functional, but not practical. So, for a few extra dollars we added a launch button.

The launch button

We bought a small plastic box from a dollar store. From Radio Shack we purchased a push button momentary switch from Radio Shack (4 switches for \$3.39) and a pack of 9 volt battery connectors (5 for for \$2.69). I drilled a quarter inch hole in the back of the case for the cord and one in the top for the button switch.

One battery will open the valve is the sprinkler leads are connected directly to the battery. But there is more voltage drop across the long connecting cord, so two batteries are required. The 9 volt batteries are wired in series, like this.

I used a long phone cord to connect the button to the sprinkler valve. I tied a knot in the cord inside the box so that pulling the cord doesn't put any stress on the switch. I used an Xacto knife to expose the wires in the phone cord and then spliced one end to the valve and the other to the battery leads.

This was our final launcher built for less than \$20, and the launcher system which cost a few more dollars.

We quickly made the rocket in the photo out of paper, a file folder, and tape just to test the launcher. We also like to launch Cheetos! When we have a function that requires a lot of rockets, we usually buy the rocket bodies from It's a Blast.

Further Improvements

In this design the launcher is connected directly to an air compressor. When we actually used this launcher for an event we added a small hand valve so that if the launch button was held down it wouldn't drain the compressor tank.

This launcher works great and it doesn't cost a lot of money to build. It has provided hours of entertainment.

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## Saturday, August 4, 2012

### Hydro Priming Seeds With Cheetos

Hydro-priming is the process of soaking seeds in water before planting. Hydro-priming decreases the time it takes seeds to germinate. For this experiment, we wanted to test how different concentrations of Cheetos in the water would affect the germination rates of pea seeds. Do you expect that Cheetos will help or hinder the germination of seeds?

Materials

For this experiment we used:
700 snow pea seeds
7 plastic cups
8 plastic bags
7 paper towels
1 meat tenderizing mallet
30 Cheetos Puffs
Sharpie to label bags and cups
A squirt bottle

Process

First we labeled each of the cups as follows: Dry, 0, 2, 4, 6, 8, 10. For each cup, we put the indicated number of Cheetos in a bag, then used a meat tenderizing mallet to smack the Cheetos into powder. We then dumped the Cheeto powder from the bag into the appropriate cup.

The next step was to add 1/2 cup of water to cups 0 - 10. No water was added to the cup labeled "Dry." The solutions were thoroughly mixed.

Next, 100 snow pea seeds were added to each cup, making 700 seeds total. The seeds were stirred into the solution. We let the seeds soak overnight.

The next morning we drained and cleaned the seeds from their solutions. The dry seeds were not washed. Seven paper towels were prepared by wetting them and then wringing them dry. Each cup of seeds were spread into the center of one of the moist paper towels. The towels were folded in around the seeds and placed in a resealable plastic bag. Each bag was labeled to identify the Cheeto concentration in which the seeds had soaked.

Every 12 hours the seeds were removed from the bags so we could count the number of seeds that had germinated. The germinated seeds were removed and the results were recorded. The remaining seeds were misted with a squirt bottle to keep them moist, then rewraped in the paper towel, and put back in its plastic bag.

Results

Here are the results. Click on the table to make it larger.

Here is a graph of the same information.

Observations

The seeds that soaked in the densest concentration of Cheetos were the only seeds that germinated after 12 hours. These concentrations also germinated the highest percentage after all but one of the periods. None of the seeds that were not primed germinated after 48 hours.

It was hard to determine if a seed had germinated. We counted it if part of the root had extended from the seed. If we were to do the experiment again we would only count them if the root were a specified length. Also, since there were so many seeds that germinated between 24 and 36 hours it might have been helpful to count the seeds every 6 or 8 hours, instead of every 12.

Conclusions

Hydro-priming definitely makes a difference. We think it is also safe to conclude that seeds primed in a solution of Cheetos germinate faster, and a higher percentage of seeds germinate compared to seeds primed in tap water. Further experimentation would be necessary to determine if the Cheeto primed seeds would be more healthy, or if the mature peas would taste like Cheetos.

## Tuesday, July 24, 2012

### Can Cheetos Keep a Car Afloat?

It is impossible to do most anything now without wondering if there is some way to relate it to a Cheeto experiment. Recently we went boating on a beautiful lake. Today we tried to answer the question:

How many bags of Cheetos would it take to keep a Honda Fit afloat?

A Honda Fit has a curb weight of 2423 lbs. What would be your guess? In the group of people we asked there was a low of 500 bags, and a high of 500,000, an average of 53,800, and a median of 10000 bags.

The Experiment

To do this experiment we used a cooler, a large bag of Cheetos Puffs, two hangers, and a measuring cup.

1. We filled the cooler about half full with water.
2. We put the unopened bag of Cheetos into the cooler.
3. We used the hangers to completely push the bag of Cheetos underwater.
4. We marked the water level.
5. We removed the Cheetos from the water.
6. We measured how much water it took to fill the cooler to the mark.

Results

Archimedes' principle states that the upward buoyant force will be equal to the weight of the displaced water. Google helped us find the weight of a gallon of water, 8.345 lbs. It took 26 cups of water (1.625 gallons) to fill the cooler to the bandaid. 8.345 * 1.625 = 13.561 lbs. Each bag of Cheetos weighs 9.75 ounces or 0.609 lbs. To find out how much buoyancy lift each bag of Cheetos provides we will take the total displacement weight of the bag of Cheetos minus the weight of the bag.

13.561 - .609 = 12.952 lbs total buoyancy.

To find the total number of bags required we will take the total weight of the car, 2423 lbs, and divide the total buoyancy of one bag of Cheetos, 12.952 lbs.

2423 / 12.952 = 187.075 bags of Cheetos. Since we don't have fractional bags of Cheetos we will round up to 188 bags. 188 bags of Cheetos will float a Honda fit.

How many bags would it take to keep your car afloat?  Google "curb weight" and the name of your car. Divide the curb weight by 12.952 to figure it out.

This is a simple experiment and was entertaining for everyone involved. It was easy have lots of parts for everyone to perform, and it helped to get every one's predictions first.
Now, do you think it will be possible to get Frito Lay to donate 188 bags of Cheetos so we can test our theory? Maybe Mythbusters would take on the experiment to build an actual raft with Cheetos.

## Thursday, July 19, 2012

### Cheeto Conductivity

In this experiment we wanted to find out if Cheetos conduct electricity. For this experiment we used a multimeter, water, and various other liquids.

The test to see if Cheetos, or anything, conducts electricity is easy - turn a multimeter to the connectivity setting (it usually has a symbol that looks like a speaker), and touch the probes of the multimeter to a different side of the thing you are testing. We touched the probes to either side of a Cheeto and quickly determined that they do not conduct electricity.

To make the experiment a little more interesting, we wanted to determine if Cheetos resist or help the flow of electricity through water. This was our experiment.
1. We taped the leads of our multimeter against the sides of a plastic cup.
2. We filled the cup with water to the point were water was touching both leads.
3. We turned the meter to 2000 ohms and measured 251. This was our baseline.
4. We then crushed up several Cheetos.
5. We added the crushed Cheetos to the water and read the new measurement. It was 165.
Because the value of resistance went down, that would indicate that something in the Cheetos helps the electrons through the water from one probe to the other.  Substances that conduct electricity are called electrolytes.

Just for fun, we tested the resistance of various other liquids to see if they are electrolytes. Here are our results.

 Liquid Value Tap Water 251 Tap Water + Cheetos 165 Milk 260 Apple Juice 350 Vinegar 29

Observations: The values of the substances changed with time, more so on the items that are normally kept cold. To get a more accurate measurement, we should probably let the items come to room temperature before testing them.

Here's a small factoid we discovered. The resistance of milk can be used to determine the health of of a cow. Here is a link to a study that was done on buffalo cows. There is a high correlation between a higher than normal resistivity in milk and infected cows.

This was a fun project. The kids liked learning to use the multimeter, and they liked coming up with different liquids to test.

## Tuesday, July 10, 2012

### Cheeto Bike Helmets

Have you ever wondered how bicycle helmets are tested? I've wondered if it was someones job to wear a helmet while a weight was dropped from progressively higher distances onto their head. After each impact they would be asked, "Did that hurt?"

In this experiment we try to answer the question, do Cheetos make an effective bike helmet?

Many kids do an egg drop experiment in school. We figured dropping an egg would be a good helmet test. If the egg in a Cheeto helmet remained unbroken when dropped, we will assume that a head wouldn't get cracked either. We started our experiment by wrapping an egg completely in Cheetos, then wrapping the Cheetos in plastic wrap.

Then we went outside and set up a ladder. We dropped the first Cheeto helmet from 10 feet up the ladder.
We counted down 5, 4, 3, 2, 1, drop.... splat. The egg broke. We did several other drops at different heights to find the maximum distance we could drop the Cheeto helmet without the egg breaking.

8 feet was the highest distance we could drop a helmet without the egg breaking. Using a little math and Torricelli's equation we figured the velocity of an egg dropped from 8 feet.

$v_f^2 = v_i^2 + 2 a \Delta d \,$
"vi" in this case is 0. There is no initial velocity.
"a" is acceleration. The only acceleration is gravity, 32 feet / second squared.
"d" is the distance the helmet fell, 8 feet.
Plugging in the numbers
v = sqrt( 0 + 2 * 32 feet / sec^2 * 8 feet)
v = sqrt( 512 feet ^2 / sec ^2)
v = 22.63 feet / second

If the end velocity is 22.63 feet / second, how far can it go in an hour?

(60 seconds * 60 minutes) * ( 22.63 feet / second) / (5280 feet/mile) = 15.43 mph

Simplified, you can use this formula to calculate the speed in miles per hour of an object dropped from any hight "d", measured in feet: (SQRT( 64 * d) * 3600) / 5280.

Or, here is a chart.

Our experiment shows that a Cheeto helmet can withstand an impact of 15 miles per hour.  So would Cheetos make a suitable bike helmet? You would probably be alright if your head hit the ground slower than 15 miles per hour. Not only could the helmet protect your head, but imagine the fashion statement you could make in the neighborhood with a helmet made out of Cheetos. And it would be a convenient snack!  This was a fun Cheeto experiment that didn't take a lot of time.

For those wondering how bike helmets are actually tested, here is a video we found on YouTube that shows some actual helmet tests. They're not quite as fun, but are more practical. Perhaps we might do some accelerometer tests in the future.

## Saturday, July 7, 2012

### Cheeto Cannonballs

In this experiment we use Cheetos as cannonballs to figure out which angle will shoot the furthest.

For this experiment we needed a rocket launcher, modified to shoot Cheetos Balls. There are lots of plans on the Internet for compressed air rockets, such as this one from Kip Kay and Make Magazine. We built ours out of 3" pipe in a U shape. Instead of gluing most of the pieces, we opted to use threaded connections that would allow us to change the angle of the launch without repositioning the entire launcher. We added a larger piece of PVC pipe on the end that a Cheetos Balls could fit in - since they wouldn't fit in the 1/2 inch pipe used for launching rockets.

We ran a long measuring tape down the center of our yard. We constructed a large protractor out of cardboard so we could determine the angle. and we filled the launcher each time with 20 pounds of pressure.

We shot three Cheeto Balls from 10, 20, 30, 40, 50, 60, 70, and 80 degrees using 20 pounds of pressure. After shooting a Cheeto, we measured how far it went down this center tape, and the distance it landed away from the center line. Here are the results.

Our purpose in doing the experiment was to see which angle shot the Cheetos the furthest. We didn't measure how far the Cheetos traveled, only how far they went down the center line, and their offset. To determine which Cheeto went the furthest, we needed to use a little math. We had two sides of a right triangle, A and B. Pythagoras came up with the equation to find the length of side C: A squared + B squared = C squared. (This is an interesting YouTube video on the subject, explaining how Pythagoras did not think about his theorem the way we do.)  We applied Pathatoreans theorem to get the actual distances.

 Degree Left -1, Right 1 Center Distance Offset Computed Distance 30 1 630 68 633.66 20 1 604 54 606.41 40 1 588 69 592.03 30 1 584 21 584.38 20 -1 567 -51 569.29

Why didn't each Cheeto land in the same place if shot at the same angle with the same pressure? There was a slight breeze, which might have helped some Cheetos and hindered others. Also, though we tried to always fill the launcher to 20 lbs, there could have been variations.

Why didn't 45 degrees shoot the Cheetos the furthest? The higher the Cheetos went, the more opportunity there was for the breeze to change its course. As Yogi Berra said, "In theory there is no difference between theory and practice. In practice there is."