100 Days of Science #9-- Wind Tunnel

We tried another fun science experiment that shows how wind can create a tunnel through two tall skyscrapers and cause them to want to pull towards one another.

We talked about how architects would need to keep this phenomenon in mind when drawing up plans for city buildings.

For this experiment we needed:

2 balloons
some water
some string
a pole
two matching chairs
empty paper towel tube (optional)

We put a bit of water in our balloons and blew them up.  Then we suspended the balloons from our pole (we used a broomstick) and made sure they were spaced just a few inches apart.

We only added enough water to keep the balloons somewhat weighted down and steady (you can see in this photo that it didn't take much water).

Once we were happy with our balloons we tried blowing air through the middle of them, sometimes using a paper towel tube. 

I honestly thought this experiment was going to be a failure. Both Evan and I could not get the balloons to move at all when we blew next to them.  Then Alec came over and gave a great big blow and we watched the balloons pull so close together they actually touched a time or two!

I had to take a moment to laugh like crazy over the faces Alec was making as he was blowing!  They were cracking us all up but I was so happy to see the experiment working!!

Here's how it works:  the wind going through the balloons is at a higher speed and when gases move at higher speeds that they loose pressure.  BUT the air on all other sides of the balloon have the same air pressure they always had and since the outside forces have greater air pressure they push inward when the air is moving quickly through the gap in the balloons and that forces the balloons together.  

It was pretty neat to learn that architects have to take this wind tunnel effect into account when designing skyscrapers because changes in air pressure can put added stress on city buildings.  

Others in this series:

1. Bernoulli's Principle
2. Ecotarium Trip 
3. Air Molecule Experiment
4. Kitchen Science
5. Corn Maze Field Trip 
6. Birds of Florida 
7. Making Static Music
8. Un-Make It Monday

10. Biomes Marine Biology Center Field Trip  

11. Disappearing Coin Trick and the Science Behind it. 

12.  Snuff Out a Candle with Baking Soda and Vinegar

13.  Making Plastic from Milk

14.  Pencil in the Rice Friction Experiment

15 & 16.  Two Experiments using SNOW

17.  Making an Iceberg 

18.  Making an Egg Float

19.  Looking at Microscopic Organisms 

20.  Eco Plant pals

21&22.  Two Experiments with Cotton Candy

23. Springfield Science Museum Trip

24.  Teaching Children the Signs of Spring

25.  Color Changing Slime

26.  Growing Tickle Me Plants

27.  Learning About Soil Sampling

28.  Making Super Bouncy Balls 

29. Exploring the New England Shoreline

30.  Color Changing Flower Experiment 

31.  Roger Williams Zoo Trip

32.  Edible Silly Putty 

33.  Raising Tadpoles

34. More Microscope Fun

35. Making Homemade Ice Cream

36.  Observing Plants Breathe 

37.  Trip to Save the Bay Exploration Center and Aquarium

38. Making Fresh Peach Preserves 

39.  Making Solar S'mores

40.  Growing a Crystal Garden

41 & 42.  Jolly Rancher Candy Apples and Lollipops

43.  Volcanic Lemons 

44.  Oozing Pumpkins 

45.  Growing a Germ Farm

46.  Looking at the Germ Farm Under a Microscope

47 & 48.  Building Model Molecules Two Ways 

49.  Kitchen Chemistry Experiments 

50.  Fall Leaf Chromatography 

51.  Color Changing Experiments with Iodine

52.  Learning About Birds in Winter

53. Iodine and Starch Experiment
54. Flouride and Calcium Experiment
55. Botanical Gardens in Winter
56.  Making Cell Models
57. Which Has More Water; Ice or Snow?
58. Exploding Snow and Water Baggies
59.  Exploring Minerals
60. Visiting the Hartford Science Museum
61-63. 3 STEM Bridge Challenges
64. Making Models of the Earth
65. Plate Techtonics with Graham Crackers
66.  Homemade Lava Lamp
67.  Science Movies We're Watching
68. Index Card Towers
69.  Botany at the Botanical Gardens
70. Best Board Games for Science 
71. Homemade Frozen Yogurt Pops
72.  Starburst Rock Cycle 
73. & 74. Sinking a Marshmallow
75. Jumping Conversation Hearts 
76-78. Building a Paper Airplane 3 Ways 
79. Learning About Hummingbirds 
80.  Planting an Herb Garden 
81. Mushroom Spores 
82. - 84.  Penny Saturation Experiments 
85. Sink or Float?
86. Disappearing Ink 
87. Sedment Layer Jars
88. Tie Dye Science 
89-91. DNA Experiments 
92.  Homemade Butter 
93. Floating Marker Art 
94. & 95. Oil Spills & Water Filtration 
96.- 98. Making Rock Candy & Rock Candy Experiments 
99. Rocket Science 

100. Permaculture Garden Tour