On Survey Forms and the Final Lab Meeting

March 18, 2011; 8:30-11:30; NIP R108

Today was the last official lab meeting since classes would end next Tuesday. This meeting, we were quite chill because we didn't have to perform an experiment- we just had to answer a set of surveys documenting our satisfaction with the lab course in general and also the things that we learned in the duration of the course.

He also gave us a calculus evaluation which I found pretty useful. Considering that our final exam for Math 53 is next week, the evaluation opened my eyes that I have forgotten a great deal about differential calculus.

Sir Pacho also told us the itinerary for the following week- our creative work presentation in front of the panel and our practical exam. I,for one, am quite nervous for both of these tasks primarily because the two have a big impact on our final grades. Considering my performance for the whole semester, I don't think that I have performed as well as I could.

I learned a lot from Physics 101.1, particularly the topics about error and scientific paper writing. It made me realize how hard it is to write a formal paper given limited time. Overall, this course was challenging yet rewarding at the same time.

On Densities and Archimedes' Principle

March 11, 2011; 8:30-11:30; NIP R108

This meeting marked the day of our special project wherein we decided to perform an experiment on fluid mechanics, specifically an experiment goaled at measuring the mass of a lemon and a block of wood by noting the buoyant force they give when immersed in three different liquids, namely, water, alcohol and cooking oil.

The first thing that was done was to measure 100 mL of each liquid in each beaker and noting the mass that the liquid contributed. The mass divided by 100 mL constituted the density of the liquid. After which, we measured the theoretical masses of the lemon and block of wood. Then, we immersed the two objects in each medium. We noted the volume of liquid displaced and multiplied it by the calculated density of the fluid. This was the density of the object at hand.

Archimedes' principle states that when an object is fully or partially immersed in a fluid, the fluid exerts an upward force equivalent to the object's weight. This principle served as the basis for our experiment, and we actually tried

to immerse three different objects, the other one being a chunk of styrofoam. Unfortunately, the styrofoam was too light to exhibit a nonnegligible volume of liquid displaced. We needed more precise measuring tools.

I had a very hard time speaking this meeting because of two big canker sores in my mouth, which caused me to be really uncomfortable the whole meeting, actually the whole day. Apart from that, it was also during this meeting that Mac and I were reunited with Peter. The three of us were quite efficient as a group, each member having a definite role to perform.

Admittedly, I was really confused with the concept at first, since fluid mechanics isn't (and I think never will be) my forte. Still, I performed my part and got it all together in the end. The experiment was smooth sailing and we finished ahead of time.

On the Special Project

March 4, 2011; 8:30-11:30; NIP R108

We were late this meeting, thereby our promise that we wouldn't be late this meeting was broken.

There were no experiments performed this meeting nor there was a discussion of some sort. Our primary goal this meeting was to think of an experiment that we would perform next week that would demonstrate our knowledge on the topics of 101.1.

It may seem easy at first, but, really, it's not. One of the most difficult things for me to do in a science class is to think of some novel idea/experiment. This problem is rooted back in HS wherein we were supposed to think of something like this every year. Seldom did I think of something immediately; I needed some assistance from my teacher when thinking of an experiment.

Here in 101.1, the experiment was to be performed as a group, therefore I would be accompanied by bright physicists that would possibly concoct something great in their minds. After incessant brainstorming, one group member suggested that we do an experiment on fluid dynamics- finding the density of an object by immersing it in an oil and water solution by pressure analysis.

It was really awesome that Sir Pacho accepted the idea because we were the last group that did not have an experiment yet.

I am really happy that no technical paper is needed next meeting, therefore it would be a sure thing that we wouldn't be late.

On the Center of Mass and Torque

February 18, 2011; 8:30-11:30; NIP R108

For the nth time, we were late this meeting because we had to finish the technical paper. Fortunately for us, though, the experiment this meeting was not really that demanding. We finished quite quickly and made up for the lost time brought about by us being late.

The goal of the experiment this meeting was to calculate the mass of a meterstick in a set-up wherein the meterstick was suspended from a height and was supported in its fulcrum point. We first had to determine the meterstick's center of mass (the point where mass is concentrated) by finding the right spot in its body wherein the meterstick, being suspended mid-air, was balanced. After that, we changed the fulcrum point and added weights to both sides, then carefully finding the positions of the weights that would balance the meterstick. We performed this part two times and took the average.

The mass of the meterstick could be calculated by equating all the torque (clockwise and counterclockwise) to 0, since the whole set-up is in equilibrium. The only missing term in the equation is the mass, and it could be derived with simple algebra.

Using an electronic balance, we measured the true mass of the meterstick. To our pleasant surprise, our calculated mass was only off by less than 1 percent.

After this, we were tasked to make the mass of the meterstick nonuniform - which was done by placing a weight on it- and then calculate the mass of the meterstick+weight by adding weights and by equating the torque with the aforementioned condition (torque=0). We only performed one trial because we were quite confident of our calculations. We, then used the balance to calculate mass, and once again, we were only off by less than 1 percent.

My friend and I made a promise that we would not be late next meeting. In turn, it was also a promise that we would not rush our technical paper and cram the night before.

On Harmonic Motion and Pendulums

February 11, 2011; 8:30-11:30; NIP R108

Because I was quite late this meeting, it was quite disorienting to see my other labmates already starting a new experiment as I entered the room. The setup that I chanced upon seeing involved a stand, a pendulum, a set of weights and a string. Immediately, simple harmonic motion entered my mind - this week's experiment was all about pendulums. It was something very familiar to me since I already did a variation of this experiment back in High School.

Mac and I formed a new group, since both of us were late. Peter, our other group mate, was absent this meeting. We went upstairs to the physics instruments room to get the setup and what greeted us inside the room was a very upset and grumpy man who handled the materials. I don't want to rant about the old man but it seemed as if he was grumpy for no apparent reason. It irritated me a bit as to how he acted- it was unethical, yes, and also quite unnecessary.

After getting the materials, we went back to the room and started the experiment. Basically, what we were supposed to do was to vary the length of string, angle of displacement, and weight of bob one at a time to see their effect on the period of oscillation.

Since there were only two persons in our group, both of us had to do something. Mac measured the period of oscillation, while I fixed the angle of displacement and released the bob. Like all the other experiments that we have performed, this one was very routinary and involved trial upon trial.

The motion of a pendulum could be described by a mathematical equation:

T=2*pi*sqrt(L/g)

where T=period, L=length of string, and g=gravitational acceleration.

As we can see from the formulation, the only major contributing factor to the period is the length of string. Their relationship is direct- increasing L increases T. After some research, I also discovered that T is also affected, to some extent, by the angle of displacement, i.e. the equation only works for small angles of displacement. For large angles, more complicated mathematical formulations that involve Taylor expansions and infinite series are required.

The data that we gathered, as far as I can remember, are not that concise with the theoretical expectations. We measured slight increases in period of oscillation as we increased the mass. This could be attributed to error in release of bob or in measurement of time.

Since we were late for the meeting, we were unable to test the scenario wherein the length was very, very high, thereby we had to merge with Robby's group to share with their data. It was very fun because the setup was too big for R108; we had to go to the second floor and hang the pendulum from that height. Admittedly, the setup was quite dangerous since the bob could fling from the string and hit bystanders, but still, it was very fun. For this setup, I was assigned to measure the period of oscillation.

I prefer this experiment to the two previous projectile motion experiments because

1. I was reunited with my old group, even if the other member was absent

2. I was more useful in this experiment

3. the setup was generally more fun (particularly the large L setup)

This new experiment implied that we had to, again, submit a technical report next meeting, something that I'm really not that enthusiastic about.

On Projectile Motion, Part 2

February 4, 2011; 8:30-11:30; NIP R108

This meeting was basically another one devoted to experimentation concerning projectile motion. This time, we were tasked to measure the y-component (height) of the projectile as we vary the x-component (range) while, in turn, varying the angle four times (0, 15, 30 and 45 degrees). This was arguably an easier task since the ball (projectile) was flung to the wall, therefore it did not go to far-off places like last meeting.

If we know the x and y components and the angle of the projectile, its initial velocity could be computed. From my last post,

Y=X*tanA-0.5g*(X/(Vi*cosA))^2

We know X, Y and A, therefore the only missing term in the equation is the initial velocity.

We encountered difficulty with the "projectile gun" or whatever it is called because it disassembled itself every now and then, therefore the tightness of the spring in the gun varied, in turn, varying the force (and the initial velocity) in which the ball was released. This arose when we were measuring the height with the angle of inclination at 30 degrees. We had erratic data during this part, i.e., the distance fluctuated up and down (due to the varying force) where it was supposed to resemble a parabola with simply one peak.

We were very efficient as a group, finishing ahead of time and encountering little difficulty apart from the aforementioned problem. I was also more useful this lab meeting- I was responsible for recording and encoding the data for my new group. I also became less shy with my group mates, mainly because they were very friendly with me. The initial awkwardness I felt with them last meeting was gone, and I hope that when we begin writing the technical report, I hope that my awkwardness with them would be gone, too.

This meeting made me realize how demanding physics research is. It was very tedious to repeat the same steps over and over again, therefore experimentation could be regarded as a test of endurance- it shows how dedicated one is as a scientist.

On Projectile Motion

January 28, 2011; 8:30-11:30; NIP R108

My friend, Mac, and I were late this meeting because we finished the technical paper on the determination of g which, to our surprise, was not really due this meeting. It was sort of a relief because this allowed us to do some revisions.

When we entered, an experiment was already on its way. It involved a pump that was set to a variable angle and a metal ball was placed on the receiving end. When the pump was released, the ball would be flung and the distance it traveled was measured using a sheet of carbon paper.

The experiment was a display of projectile motion, which is the superposition of x and y motion. This two dimensional motion could be split up into its x and y components since the two are independent of each other. There is no x-acceleration while g is the y-acceleration.

The range (the x-distance) is computed as

X=Vi*cosA*t, where A is the angle of inclination

while the height (the y-distance) is computed as

Y=Vi*sinA-0.5g*t^2, where A is the angle of inclination

Rearranging the terms in the first equation, we can find t and plug it into the second equation

Y=X*tanA-0.5g*(X/(Vi*cosA))^2

The values that we know are X and A, we do not know Y and Vi. We have to perform another experiment to find the value of Y or Vi to completely describe the system.

I was unfortunately separated from my group and was put into another. I really felt uncomfortable with my new group mates because I didn't know them.To add to that, I was not in my optimal setting because I didn't sleep that well the night before. Thereby, I wasn't really functioning that well and just became a pawn for them. I hope that I would be reunited with my old group the next meeting.

I realized this meeting that it is very difficult for me to work with people I barely know.