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# Creating a Top

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Wow! It is already December and we are working on rotation in class! Last year, this unit was one of the worst for me because I truly did not understand any of the concepts. I have started to figure out some of the equations and concepts but, I am going to have to work hard all this week in order to really understand the unit.

In class last week, Mr. Fullerton gave us a challenge to solve. He gave us a pencil, two small paper plates and six pennies. Our task was to make a top that would spin for a longer period of time from those materials. For the blog post this week, we have to explain how this activity relates to the engineering design process. If I am being honest, I had no idea what it was and typed it right into the handy dandy Google. I found a website (sciencebuddies.org) which gave me the steps to the engineering process.

Those steps are:

• Define the Problem
• Do Background Research
• Specify Requirements
• Brainstorm Solutions
• Choose the Best Solution
• Do Development Work
• Build a Prototype
• Test and Redesign

I definitely think that all of these were used in the activity with some of them slightly combined and happening all at once. Our problem was creating the top that would stay spinning for more than just a few seconds. Our research came from the information that we could see coming from the actual top and our background knowledge from the physics we had been learning. The requirements came in the form of the items we could use to make the spinning top which were the pencil, paper plates and pennies. The next few steps were combined because of time and we began to use trial and error to try and build the top. Brandon and I immediately knew that the the plates would have to have the pencil going through the center. We tested out where the plates would have to go on the pencil and eventually found that it had to be placed towards the bottom of the pencil. On the plates we tested the different distances of where to put the pennies and ended up putting the pennies at about an even distance towards the outside of the plates. Our final aspect that we fixed to make the top spin longer was put a small piece of tape at the tip of the pencil to keep it from spinning around all over the table. After that, we had created a top that spun for a decent amount of time with the many aspects we changed and tested.

The next question we have to answer is relating this activity to moment of inertia and angular momentum. For the moment of inertia, the mass and radius are the factors that change moment of inertia. Since we could not really change the mass of the object, spreading out the pennies to create a larger radius impacted the moment of inertia for our top. For the angular momentum of the top, the moment of inertia and angular velocity impacted the top and allowed it to spin for a longer period of time. These two concepts combined created the top with lots of trial and error for the perfect one.

Until next time,

RK

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