How long does it take to empty a soda bottle full of water? You’ll amaze your dinner guests and explore some of the scientific properties of air and water when you learn how to empty a full bottle of water in just a few seconds!

## Experiment

### 1

Start with two empty, plastic soda bottles. Smaller size bottles work well for smaller hands, but the Twister Tube works on most sizes of plastic soda bottles. Make sure the bottles are the same size.

### 2

Fill one bottle 2/3 full with water, attach the twister tube. If you don’t have a Tornado tube, skip ahead to step #4 for instructions.

### 3

Attach the second bottle to the other end of the Twister Tube. Make sure that the bottles are screwed on securely so that the water does not leak.

### 4

If you do not have a Twister Tube, place a metal washer on top of the bottle with water. Turn the empty bottle upside down and align the openings of the two bottles.  Connect them by wrapping them tightly with duct tape.

### 5

Quickly turn the bottle over and set it on a table or desk so it’s standing vertically. A few drops of water might fall into the lower bottle, but not much.  Start moving the Twister Tube in a circle, as if you were stirring something on the stove. At some point, a twister (called a vortex) will form and water will start spiraling into the lower bottle. It looks just like a tornado!

## How Does It Work

If you’ve ever watched the water drain from the bathtub, you’ve seen a vortex. A vortex is a type of motion that causes liquids and gases travel in spirals around a center line. The vortex in this experiment is created when gravity pulls a liquid through an opening to form a rotating tornado.

Swirling the water in a bottle while pouring it out causes the formation of a vortex, making it easier for air to come into the bottle and allows the water to pour out faster. If you do not swirl the water and just allow it to flow out on its own, then the air and water have to essentially take turns passing through the mouth of the bottle, thus the “glug-glug” sound!

## Take It Further

Take it Further #1 – Great Pour Challenge

What You Need:

Great Pour Challenge Instructions:

1. Fill the soda bottle to the top with water.
2. Here’s the challenge: How long will it take to empty all of the water in the bottle into the pitcher on the table? Record your prediction on a piece of paper.
3. Without squeezing the sides of the bottle, time how long it takes to empty all of the water. You might want to repeat this several times to validate your time.
4. Then, fill the bottle to the top with water just as you did before. However, this time swirl the water by moving the bottle in a clockwise or counter- clockwise motion while the water is pouring out. Keep swirling the water until you see the formation of what looks to be a tornado! The water begins to swirl in the shape of a vortex and flows out of the bottle. Record your time.
5. Compare your times. Was one method quicker than the other? If so, why do you think you got these results?

Take it Further #2 – Twist of Color

What You Need:

Twist of Color Instructions:

Repeat the original instructions, but this time try adding 2 ounces of colored lamp oil to the water. Lamp oil is available at most department stores where oil lamps are sold. The oil will float on the surface of the water since oil is less dense than water. When the oil and water swirl together, the less dense oil travels down the vortex first and creates a “colored” tornado effect.

Take it Further #3 – Flying Objects

What You Need:

Flying Objects Instructions:

What would happen if you put an assortment of small objects in the bottle with the water? Will the objects that you put in spin to the center of the vortex or to the outside of the vortex? Make your predictions, then follow the original directions but add in some small objects to the bottle with the water and try it to find out.

Take it Further #4 – Styrofoam Bead Timer

What You Need:

1. Carefully open the bottle with the beads.
2. Twist on the large connector.
3. Twist on a dry 1 liter soda bottle. Turn it upside down to make your own soda bottle timer.
4. Now, check and see if this timer is accurate. Is this a good way to measure time? Why or why not? How can we test this?

To take it one step further, you may want to add water and see how this timer compares to the dry timer you have right now!

1. Move as many of the beads to one bottle as possible.
2. Over the sink, add water to the bottle without beads. Fill to the brim.
3. Add water slowly to the bottle with the beads. You are filling in all of the little spaces in between the beads. As the beads start to push themselves out of the bottle, slow the water and finish filling to the brim.
4. This is where it gets tricky – you have to connect the bottles. Carefully attach the Tornado Tube to one bottle then connect the remaining bottle. We suggest doing so over a sink until you get the hang of it.
5. Now, check and see if the this new water filled timer is an accurate timer? Is this an accurate way to measure time? Why or why not? How can we test this? Is it more accurate or less accurate than the dry timer? Why do you think you are seeing these results?

## Science Fair Connection

While creating a swirling, twirling vortex of water in a soda bottle is fun, it isn’t a science fair project. You can create a science fair project by identifying a variable, or something that changes, in this experiment. Let’s take a look at some of the variable options that might work:

1. Compare the time it takes to empty the water from one bottle to another using the different sizes of Tornado Tubes– one with the large opening compared to the one with the small opening. You may want to also observe and note how the vortex looks during each trial.
2. Try using different sized bottles and determine how that affects the time.
3. Determine the quickest way to transfer the water from one bottle to another. Try it out– shake, twirl, tip, squeeze. What is the fastest method?

These are just a couple of ideas, but you aren’t limited to them! Come up with different ideas of variables to test and give them a try. Remember, you can only change one variable at a time for each test. For example, if you are testing different sized bottles, make sure that all other factors in the test remain the same!