Calorimetry Challenge

The goal of the Calorimetry challenge is to design, build, and test a calorimetry setup to measure the heat given off in a chemical reaction. Using an arduino, we need to code an immersion heater and stirring rod to control temperature. All of this needs to be done in a Styrofoam cup.

Final printed pieces

To start, we used Autodesk Inventor to 3D model the cover and stirring rod of the setup. The cover needed a place to hold the immersion heater and allow for a thermistor to pass through, while the stirring rod needed to mix the heat throughout the water. We based a lot of our designs on the example provided to us in class. The only inconvenience was trying to accurately measure all dimensions of the cup. It was time consuming, but we were able to do so using a caliper. The above mentioned thermistor needed to be wired into a voltage divider circuit and monitored by an analog pin on the arduino; the transistor-mechanical relay circuit needed to control the immersion heater through a digital pin on the arduino. The first time through, we accidentally forgot to change the units in Autodesk to inches. The piece printed in millimeters and was extremely small. Then we had to restart both pieces because we forgot to save the originals. On the right is are pictures of how the parts appeared on Inventor. Below is an image of the final printed pieces.

Next we completed the Thermistor Calibration. First we wired the thermistor on the breadboard and wrote a code to get corresponding values of Serial Monitor readings at various temperatures. Here is a copy of the code. We placed the thermometer inside the warm water and got the initial temperature (in degrees Celsius) and the Serial Monitor reading. As the water cooled, we gradually collected more data points. Once we had enough data, we graphed the points and found the equation y=0.352x-153.073. 

We finished wiring the general Arduino setup using this guide. The goal was to make a mock-up experiment where we'd light up a large bulb instead of the immersion heater. To do this, we wrote a program that puts heat in for 10 seconds, then stirs for 10 seconds, then puts out a temperature and total heat added in the Serial Monitor. Once the mock-up worked, we replaced the bulb wiring with the immersion heater one. The video of our experiment can be found here. The image below was our final successful setup.

Transfer the Load with Winch Challenge - Day 5

Today was the final trial of the challenge. My partner and I had completed the initial requirements last class, so this time, we focused on gaining bonus points. Any team that lifted more than one mass would receive those points. Previously, our robot did not complete more than one cycle due to uneven weight distribution; the robot was top heavy. 

Below is a video of our robot completing two cycles of the challenge. It lifted a total of 400g (200g per mass). 

Final Thoughts 

I had more fun in this challenge than the first one; however, it was a lot more difficult. The robot was different than all the one's we created before, especially since it was not car-based. This time, we had to apply our knowledge of gear ratios in order for the robot to properly function, and we had to conduct multiple calculations.

Performance: As previously mentioned, our robot completed all requirements in order to receive full credit. Throughout the building process, we directed our focus to weight distribution and stability. We added counterweights to various places, allowing the mass to be lifted steadily. If we were to do this challenge again, we would more closely focus on the string that lifted the mass; it kept on slipping, limiting our robot to completing only two cycles.

Improvement and Learning: Thanks to this challenge, I am proud to say that I now understand the concept of "torque", for it is something I never understood before. To put it as my partner did, we also learned a lot about patience; taking apart and rebuilding practically defined our Winch Challenge experience. Because this trial was more successful than the last, I hope that my robot-building skills continue to increase as I move onto the next challenge. 

Illini Motorsports

Today, students from the University of Illinois present to the PLTW and STEM classes. The group presenting was the team from 2013's Motorsport competition. They talked about the design process of their race car, giving us an idea of what we will be able to accomplish in a few years. The race car ran using a lithium ion battery. Last year in middle school, I took place in a car competition, but in comparison, it was in a much smaller scale. Our car also ran on a lithium ion battery. It is amazing how similar my previous experience is to these experiences yet to come.

Computer/projector set up

2013 Illini race car

Illini presenting