8/31 Back

Today was a busy day in 2nd Period Honors Physics. At the beginning of class, Coats-Haan reminded us to check the whiteboard to see whether we should turn our homework (Pg. 21 #1-5, 11-13) into the folder or if she was just going to check it. Today she just checked it. She gave us an answer key to share between ourselves and the person next to us, not because she didn't have enough papers, but because she wants us to work together. We get a lot more out of figuring out errors that way than asking her to do a problem on the board, she said. Also, if we hadn't looked at the beginning of the bell, we went up to the graded papers folders and got back our Procedures Quiz and Book Treasure Hunt. Coats-Haan checked our homework and if we had our book covered or not, because she had forgotten to remind us she wanted them covered two days ago, so she pushed it back until today. Coats-Haan asked if we were done checking and then told us how she can usually tell when people are done later in the day, but in second period people are still sleeping, so it's harder to tell.

She gave us an extra credit opportunity which involves demonstrating Bernoulli's Principle to kids under 10 years old. For the project, we have to fill a large container with water and tie off two toy boats (or tupperware) with some space in between them. Then we have to run water through a hose in between them and show the results to the children. In order to get credit we have to take at least one picture while showing the kids the experiment. It is due Sept. 30. Also, for tomorrow, we are to complete the lab on page 5 (five) of our Lab Manual. Its purpose is to learn what a "radian" actually is.

After telling us about these assignments, Coats-Haan proceeded with our notes for the day. They were on Bernoulli's Principle. She led the lesson off with a demonstration of blowing air into the back of a snake head which had little balls for eyeballs that floated in the air when you blew. The snake only had one eyeball, though, because she couldn't find the other one. Coats-Haan explained that where there is a fast-moving fluid (in this case, air,) there is low pressure. In this experiment, there is a column of low pressure around the ball that allows it to staying floating. If the ball fell one way, the comparably high pressure of the room pushed it back into the column of low pressure. We proceeded with our notes from a powerpoint presentation. Coats-Haan's definition of Bernoulli's Principle states, "When the speed of a fluid increases, pressure in the fluid decreases due to the conservation of energy." She said this is why planes fly. Since the top of the wing is longer than the bottom, air on top has to travel faster, creating lower pressure above the wing. The result is lift, causing the plane to fly. Other practical examples of Bernoulli's Principle are a roof getting blown off a house, a shower curtain getting stuck to your leg after turning the water on, and an umbrella upending during a storm.

After our notes we got to do something really cool. Coats-Haan confirmed that no one in the class had a peanut allergy (and she has about 20 witnesses to prove it) and she gave each of us two peanut M&M's. Then, like a group of students fro ma physics magazine, we got to try out the experiment with the ball. We tipped our heads back and placed an M&M on our lips and then blew. The goal was to get it to float like the snake eye. Matthew was particularly good at it and experienced the first success for our class. Coats-Haan told us that she always seems like the cool teacher because she lets us try things like that, but really she only has us try them because she's not all that good at them herself (her words, not mine.)

After this we worked on our kites. All that the groups had left to do was punch a hole in the tape on either side of the kite, thread sting through each hole and tie it to a flying spindle. After completing this we walked outside (silently) through Main Street and continued to the top of the hill on the north side of the parking lot. For a couple minutes we all tried to fly our kites. Matthew's group was the first to achieve significant lift-off, but most groups were soon to follow. After that we went back inside and got to the room right as the bell rang, throwing the paper and tape from our kites in the trash, but saving the dowel rods.

In regards to the question of the day "How does Bernoulli's principle apply to the flight of your kite?", I think that I have a pretty good idea of an answer. Similarly to the airplane wing, the air on the top side of the kite is traveling faster than the air on the underside of the kite. This creates a pocket of lower pressure above the kite and the higher pressure underneath helps push the kite upward in an attempt to equalize the pressure on the two sides of the kite. However, moving air is required for the kite to fly, and we didn't have very much of it in class today.