The objective of the lab TheNightKing and I performed this week was to create a functioning top with the given materials of a pencil, 2 paper plates, 6 pennies, and tape. In relation to the engineering design process this would be the problem or objective we need to focus our ideas around.
Our next step would be research, but , due to our lack of time, we pulled from our knowledge gained throughout this past unit and our previous year physics. One of the main principles to keep a top up is angular momentum. The equation for spinning angular momentum is rotational inertia x angular velocity. So we need to spin it as fast as possible and, most importantly, we need to give it the largest quantity of rotational inertia possible. So, ignoring the pencil rod at the moment and plates, we knew we needed to get the pennies as far away from the center as possible since the equation of a mass away from the axis of rotation for a given mass is mr^2. So, by increasing the radius, we could get a larger quantity of spinning angular momentum.
Stating and listing the requirements would be the next step in the engineering process, but we were already given them in the objective.
The next step is to brainstorm, evaluate, and choose solution. We chose to use the pencil as our main post and then centered and poked it through the two plates. We then taped the pennies to the outskirts of the plate as this would put their mass at the farthest points away from the center of mass as possible.
Our prototype was created and now we began testing. The top originally wobbled so much that it wouldn’t spin so we adjusted the pennies. We Adjusted until we had the top balanced which decreased the wobble dramatically. That being said, it was not as stable as we ideally would like. This is when FizziksGuy gave us a nudge in the right direction by asking which part was the most unstable. We both noticed that it was the very top of the pencil. In our efforts to make the top more stable, we broke the pencil to a fourth of the size and therefore dramatically lowering the center of mass. Now the top was much more stable as the distance of the center of mass from the ground is substantially less than before.
After all this testing, we felt our top was substantially more stable and adequately addressed the problem, being able to spin for longer than 30 seconds at a time. The last step in the engineering design process is communicating our results which coincidentally are all explained above. Engineers are used not only to create solutions, but to improve on the efficiency of current ones, so to this effect, had we had a longer time frame I am sure the results could have been even better.
As always thanks for reading! - ThePeculiarParticle