Tuesday, November 15, 2011

Wind for Schools

The following is a brief summary by Alex from the website Wind for Schools
With the knowledge that the future of our energy lies within the children of today, the U.S. Department of Energy’s Wind Powering America Program developed the Wind for Schools program in 2006. The main objectives of this program include: to encourage university-level wind education and training, to promote on-site education at the K-12 level by installing wind systems at schools unable to fund them on their own, and to support K-12 wind energy education in schools with installed systems and surrounding schools. This program is currently operating in eleven states, and is open for starting in other states. The most used and recommended product for schools wishing to participate is the Skystream wind turbine. When schools install this, they also get a full communication system which allows students to monitor the performance of their turbine and energy consumption. This is a great tool for the learning community.

Saturday, November 5, 2011

Small Wind Electric Systems

The following is a brief summary by Nick of Indiana's Consumer Guide for wind systems:

Wind electric systems are not only for the big businesses and important companies; they are also for the average homeowner. If a home is sitting on land that has enough empty cleared space and wind speed, then installing a wind electric system could possible to the best option for their energy needs. If it is unknown whether or not there is enough wind speed, U.S. Wind Resource Maps is a valuable tool. The cost of installing the system depends on the height of the tower and the diameter of the rotor blade. Also, a general rule of thumb is that the wind tower will cost anywhere from 1,000 to 5,000 dollars per kilowatt on initial installation. It is recommended that a wind electric system be installed by a company that specializes in it. This is not something that should be attempted without an expertise in electricity and manufacturing. For a home wind electric system, it is suggested to use a guyed system. There are three different types of guyed systems: balance, stand-alone, and grid-connected. All three have their own benefits and it is something that a home owner should look into before deciding to install a system.

Friday, November 4, 2011

Pressure Sensor - Work

The students are doing a lab to better understand the relationship of pressure and volume, also known as Boyle's Law. They will also find work by using the Vernier DataQuest application on the TI-Nspire.

The following video shows the set up and the experiment. A screen shot showing the analysis done to find work follows.

To find the work, the area under the P-V diagram, use menu Analyze, Integral. It is important that the work is negative. Why is it negative?

Wednesday, November 2, 2011

Egg Launch and wind near a building

During the end of October, Covenant Christian High School held their annual Egg Launch, an event where students build capsules to protect eggs launched from the roof of a building. The overall goal is for distance. In addition, Physics students are faced with the challenge of limiting their egg capsule to fifteen centimeters in diameter while AP Physics students are required to construct their capsule in less than five minutes. Through this event, we learned more about trajectory, gravity, and the effects of air resistance, in addition to figuring out what materials are the most shock absorbent. Much of the challenge is figuring out how to build a capsule as small and light as possible.

On the day of the egg launch, there was minimal wind, with maximum gusts of not much more than 1 m/s. Due to the size of the egg capsules, the wind likely had a negligible effect on the distance of the egg launch. But as a well struck baseball will only travel half as far as it would have it were to travel in a vacuum, air resistance does have an appreciable effect. Overall, out of 100 eggs, 21 survived with the maximum distance being over 60 meters. Obviously their grade wasn't based on the survival of the eggs. You can read more about the rules, parameters and grading of the Egg Launch at this site.

The AP Physics still participate in this event as an enjoyable review of collisions, conservation of energy and projectile motion. They do not need to write the paper again, but they do need to do the calculations. Their rules are there are no rules except to construct the protective container in the first five minutes of class.

So while I was on the roof, I took the opportunity to measure the wind speed, as previously mentioned. I put the TI-Nspire CX CAS and the TI-Nspire Lab Cradle with the anemometer on a larger metal contraption on the roof, over 5.6 meters above the ground. As I was cleaning up, I forgot to look there for the TI-Nspire. The next day I get to school and am looking all over the place for the it. I finally figure out that the only place it could be is on the roof. I would not recommend putting your Nspire to a test like this. I'm certain it is not waterproof, but it withstood a large amount of dew as seen in the pictures below. We were praising God that the devices were created with some quality durability.