(*) Science is fun but sometimes requires caution and help from others. Remember to ask an adult to help you when experimenting.
1 liter soda bottle
Large bucket of water or access to a sink
Fill your 1 liter bottle with water. Before pouring it out, record how long you think it will take for the water to completely pour out of the bottle.
My guess is…….seconds
Without squeezing the bottle, try to pour it out as fast as you can into a bucket or sink. Repeat this three times and record your trials in seconds.
Can you think of a way (no squeezing) that you can empty the bottle faster? After you brainstorm your new method, give it a try and record your trials in seconds.
Now that you’ve tried your method I’ll let you in on my secret method to quick pouring. Fill the bottle to the top and this time when you flip it over move the bottle in a swirling motion. You should start to notice a swirling vortex is forming inside your bottle. Repeat this technique three times and record your results in seconds.
What happened to your trial times? Did the times increase or decrease? Which method worked best? For more fun; grab a friend, another 1 liter soda bottle, and have a race!
How does it work?
The swirling tornado in the bottle is referred to as a vortex, which is a type of motion that causes liquids and gases to travel in spirals around a center line. When you swirl the bottle it causes the water to form a vortex, which make’s it easier for air to come into the bottle and for the water to escape.
A vortex can be formed in many ways. Only a small amount of swirling water is needed to start one. You may have seen them form over your bathtub drain. If so, you would have seen that the water spins away from the center of the vortex. The rotating motion of the water pushes it outward as it spirals into the drain. The vortex will continue until the water is gone, unless you cover the drain or block the rotation. Did you know that water running down a drain rotates in different directions in the northern and southern hemisphere? In the northern hemisphere it would swirl counterclockwise; while water in the southern hemisphere swirls in a clockwise direction. This phenomenon occurs because of the Coriolis effect, which is the influence that the earth’s rotation has on any moving body of water or air.
Density Column: Can you stack liquids?
*adult supervision recommended
Cylinder shaped vase (large enough to hold 6 cups of liquid) or a 1 liter soda bottle
1 cup measuring cup
6 plastic cups
Karo syrup (light syrup instead of dark if possible)
Dish soap (Dawn if possible)
Measure 1 cup of each type of liquid into the six plastic cups. Each cup should only contain one liquid. You can add a different color using food coloring, to the rubbing alcohol, water, and Karo syrup for a more dramatic column. Start by pouring your honey into the bottom of the container. Now you will pour each liquid SLOWLY and into the CENTER of the container one at a time. It is very important that the liquids do not touch the sides of the container. A funnel would help. It’s okay if the liquids mix a little as you are pouring; the layers will always even themselves out. The order that you add your liquids must be as follows:
Layer 1= Honey
Layer 2= Karo syrup
Layer 3= Dish soap
Layer 4= Water
Layer 5= Vegetable oil
Layer 6= (*) Rubbing alcohol
What do you see now that you are done? How many layers of liquids are present? Do you think there is a reason for adding them in a particular order?
Often the same amount of two different liquids will have two different densities, because they have different masses. The liquids that have a higher density will sink below the liquids that have a lower density. Density is basically how much matter is smashed into a particular area, or a comparison between a liquid’s mass and volume. Remember this equation: Density = Mass divided by Volume. Based on this equation, if the mass of something increases but the volume stays the same, the density has to go up. Likewise, if the mass decreases but the volume stays the same, the density has to go down. Lighter liquids (like water or rubbing alcohol) are less dense than heavy liquids (like honey or Karo syrup) so they float on top of the more dense layers. Now that you know how it works see if you can find some other liquids in your house and experiment with their densities.