Vibration and Sound

The first part of class we discussed our study guides. We went over those very quickly. The second part of the class we did a lab. In this lab we had a metal thing that we would hit on a block of wood and then hit an object. The first thing we hit was water. The tool was dipped into the water and it made the water jump. The next thing we tried was a ball. The ball bounced back of the tool. The next item we tested was a piece of paper. The paper vibrated and made a loud noise. The noise sounded like something was touching different lines in the paper. Next, we held the tool up to our cheeks. This made a vibration on our cheeks. It felt like someone was rubbing a massager on our cheek. Next, we tried the two cups tied together with string. We hit the paper clip inside the strings. The sound and vibration went all the way across the string to the other cup. This made a semi-high pitched sound. The last thing we tried was a huge round cylinder but it was not enclosed. There was no ends. This made a lower sound noise. This lab was fun. It would be great to do with my students. The students could also bring items from home to try too!

Electroscope

Today in class we did the lab, electroscope. We needed: 4 plastic drinking straws that bend, 2 plastic 35 mm film cans, modeling clay, scotch tape, and a balloon. We first put enough modeling clay into the film canisters to fill them half way up. Then we place the straws in each canister, two in each. Then Bent the straws to make arms for each. We then took two 4 inch pieces of tape and put them on the table and leave one end off. We pulled the tape up quickly then quickly placed it on the arm of each of the straws in the two canisters. We then moved the two tapes so they are face to face and 6 inches apart. Then we moved the two cans closer together. The two tapes repelled each other. Next, we tore off two more pieces of tape off and pressed them together and then pulled them apart. Quickly we pulled the two tapes apart and placed them on the two remaining arms. These two tapes attracted each other. Next we blew up the balloon and rubbed it on our hair. The balloon repelled the piece of tape whose smooth side was in the middle of the two pieces of tape and repels the sticky side that was in the middle. From this lab we learned that positive electrons repel and opposites attract. The two pieces of tape we first put on the table and pulled off repelled each other because they both had the same charge. We also saw that the tapes we stuck together and pulled apart we attracted to each other because one was negative and one was positive.

Two Simulations

For the first simulation I did the magnet and compass simulation. When the strength of the magnet was at zero the magnet did not affect the compass at all. As you made the magnet have more strength the more it affected the compass. When the magnet was at 25% and right next to the compass it only affected it a small amount. The compass was not straight up and down or north and south. It was about two degrees off. The farther you moved the magnet the farther it got away from being north and south. The compass also moved at a slow pace with this percentage. Next I turned the magnet strength to 50%. This time when the magnet was right next to the compass it was only like one degree off from being right up and down or north and south. The farther you move it away the farther the compass gets from being straight up and down. Lastly, I put the magnet at 100%. When the magnet is set up right under or above the compass it goes exactly to north and south or up and down. No matter where you put it on the page it goes to exactly north and south or east and west. I could not get the second simulation to load on my computer.

A Good Sock

Today we restarted the lab we began last Thursday. We started off by filling our four glass bottles with water. The first test was on one with a wool sock on it and one without a wool sock. We stuck the probes in them and waited for 3 minutes. The temperatures to begin with were 43.2 for the uncovered bottle and 42.9 for the uncovered. Afterwards the numbers were 42.7 for uncovered and 42.8 covered. We took final temperature – beginning temperature and found the following answers uncovered -.5 and covered -.1. We did a second experiment with a cotton sock and then a wet cotton sock. At the beginning the cotton was 41.7 and the wet cotton was 41.2. Afterwards the cotton one was 41.5 and the wet cotton was 40.4. Again we took the final – Beginning. The answers were -.2 for cotton and -.8 for the wet. We learned that the bottle with wool had the less temperature change on the first experiment and the wet sock on the second had the biggest temperature change. This experiment showed us that wet clothing in cold weather makes you colder faster. The bottle cooled off faster than all the others by quite a bit.

Study Guide and "A Good Sock"

Today in class we went over our study guides for the first half an hour. Personally, I like when Dr. E gives us the answers than when other students give the answers. The other students are too quiet. I cannot hear them give the answers and then we move on quickly. We went over the study guide quickly today but it still helps discussing the material. As I take the quizzes I remember the information we touched on in class and the examples given. It helps to go over the study guide a lot.
The second part of the class we began a lab but we did not get to finish it. We are going to redo it on Tuesday of next week. The lab we began is called, “A Good Sock”. For this lab we needed 2 plastic bottles, one sock, hot water, room temperature water, two thermometers, and a computer. The objectives of this lab are to determine change in temperature, make a bar graph, compare the insulating properties of cotton and wool. We also will need to apply what we have previously discussed in class to answer questions.

Thermal Energy

Today in class we discussed thermal energy. We learned that temperature is related to the average kinetic energy of the particles in a substance. So if the water molecules are moving around rapidly the temperature of the water increases. We also learned that thermal energy is the total of all the kinetic and potential energy of all the particles in a substance. For example a swimming pool has more heat energy than a hot cup of coffee because it has more mass. We also talked about heat is how the flow of thermal energy from one object to another. Heat always flows from warmer to less warm. There is no cold in science. We also discussed specific heat and how some things heat up faster and cool down faster than others. The example given was sand and a body of water. The sand during the day heats up very fast and at night cools down very fast while a body of water takes a longer period of time to heat up or cool down. We learned that this is because water has 4184 J/KgC and sand has 664 J/Kg C. This is a big difference. Water particles are more compact together and it takes more energy to tear them apart compared to sand where the sand particles are not bonded nearly as well so it takes much less time to tear them apart.