Heaaaaaaaat Engine!

This time we had a relatively very fast experiment. We used the heat engine apparatus, a 100-g weight, hot and cold water bath, and gas pressure and thermo sensor. We connected all of these like the one below:

Apparently, upon making our technical report on this experiment, I found it hard to do. At first I was amused by the going up and down of the heat engine's piston. However, when I read the manual, there were many steps we had to do to interpret the data we had. The experiment itself was easy and fast. We have to first put the metal cylinder into the cold reservoir, note measurements, add weight, note measurements, put into hot reservoir, note measurements, remove weight, note measurements, put into cold reservoir, note measurements, and then the cycle is done!

Though we did it about twice or thrice because we have to read the temperature, pressure and volume simultaneously at each part of the cycle. Once the measurement suddenly deviates, we have to do it all over again. It was fun though!

Well, going back to writing the paper, it was sort of a long process -- maybe because of the guide questions we had to answer that made it hard.

Water, Ice, Water

Soooo, we did the the freezing and melting experiment on the 4th meeting of our Physics 103.1 lab class. It was quite a easy-to-do and fast experiment compared to our previous activities. On the other hand, I was extremely late that day... *sigh* I woke up 9AM whereas our lab class starts at the same time. Good thing I was still able to manage and take a bath and run all the way to NIP and end up 30 minutes late.

The Experiment

Going back to the experiment, we started with freezing water. We first took a test tube with around 5ml water and placed it on an ice bath using a iron stand just like the figure below:

this is the exact diagram of what we did in the lab!

Using awesome LabQuest, we measured the temperature of the water inside the test tube with the Thermo Sensor dipped on it. When the ice cubes on the beaker started melting, we added salt to further lower the temperature and continuously added more ice. We did this for 15 minutes. After that, we end up with a constant temperature of 0 degrees Celsius.

When set run 2 and this time, we removed the ice bath and let the ice formed inside the test tube melt. After 12 minutes, we submerged the test tube to a warm water bath. When the run automatically stopped, we were then set to analyze the data.

We then took the average of the flat parts of the two temperature vs. time graphs (which means they're constant). We came up with 0.12 degrees Celsius as the freezing point and 0 degrees Celsius as the melting point. Which is just close enough to the theoretical value.

Personal Insights
It was really, really simple. This experiment was quite straightforward, however, it was really hard to freeze the water... to actually make it solid ice. So we had to do it thrice (I think). Anyway it was literally cool to freeze water. Even though I came late, our group was still able to finish first, which is also a first. :))

Heat transfer!

Our second experiment was about investigating the heat transfer of water in an unpainted and painted (black) aluminum cans. We did two activities: one for cooling and another one for heating. The latter part was supposed to be an additional experiment, but we still had enough time to do it. :)

I. Heat Transfer for Cooling

We heated water until it temperature almost reach its boiling point. Then, we measured them to 200mL using graduated cylinders and transferred the water onto each can. Using Thermo Sensors and LabQuest, we recorded the temperature in the water inside both cans as they cool down in room temperature.

The graph we got was curved. After further analysis, we concluded that the rate of cooling is directly proportional to the temperature difference inside and outside the can. It was also observed from their polynomial trendlines of degree 2, that the unpainted can cools faster.


II. Heat Transfer for Heating

Each can was then replaced with tap water of the same volume. We then placed them in front of an incandescent lamp. Using the same device, we plot the temperature of each can for 20 minutes. The result came out with a linear a graph, which means that the rate of change in temperature in both cans is constant. By looking at the last temperature recorded, it was obvious that the aluminum can painted in black became hotter than the unpainted one. Computing for the slope of the graphs using trendlines, we also saw that the black can heats faster.

III. Personal Insights
For this experiment, it was sort of a test of patience - waiting for 20 minutes for two cans heated by a lamp. T'was kinda funny how we spent our time while waiting for them:

yeap, we're bored :p

However, putting the almost-boiling-water-it-hurts-when-it-touches you was a challenge, especially when the pot holders are kinda tearing off. :)) Over-all, we had good results and fun lab class by trying to capture people's faces (haha!)