WARNING: MEASUREMENTS ARE UNCERTAIN.

IS MEASUREMENT RELATIVE?

We're humans, the contemplators of the universe. That's it. We love, or should I say it is natural for us to invent things that were not here, not within reach to make our lives easier. Let me cite an example, alphabets. Language is an indispensable part of our existence. Can you imagine a language which didn't need the help of a symbol for giving meaning to every single word in it? It's difficult to think one, right? Another thing we wonderfully "made-up" although many of us hate this.. mathematics. We cannot deny that we were enlightened on how the universe rationally moves or goes on by using this wonderful invention. We're in great need of understanding the whole truth of our dear universe. I guess that was delivered too sentimental. In addition to that, since I'm taking up Physics, it's important to quantify things that are measurable, if it's not measurable, it's not-so-physics. Anyway, why am I saying these things? How do these answer the BIG question above? On my last post, I mentioned that measurements are products of arbitration. Which means that.. [look at the title of this new blog -- the one with the "warning"].

activity 1
 Last time, I said the three major factors that affect your measurement according on what I've learned during our discussion or basically what I wrote on my notes:

1.  The nature of the quantity being measured (e.g. a person is measuring a roughly surfaced object using a ruler *goodluck*)
2. Judgement of the experimenter (e.g.  the measured data lies between 1 m and 2 m and the experimenter decided to report the data as 1.500 m)
3. Limitations of the device (e.g. some graduated cylinders have more detailed calibrations than others)

  With these factors in mind, I realized the point I brought up, that measurements are the results of arbitration. Yes, they're just made up. However, these data gathered are very important for the technical people.

 

activity 2

  

  I already made a short narrative on how we measured every, single rice grain by using a Vernier caliper and it mainly focuses about patience, data, patience, stuck fingers, patience, oh well. The real challenge was measuring the grains using this thing: 

                                                   (image from headway-tech.com) 

A micrometer caliper. Luckily, last meeting, we had the chance to use this as a measuring tool. Although, this looks harder to use than the Vernier caliper, we (our group) ironically measured more grains using this kind. I bet we learned to be more focus this time. Anyway, like our first measurements using the Vernier, the data we collected using the micrometer corresponds to what we expected. I think 90% of the grains measured as 7.00+ mm. The other 10% are mostly dominated by the 6.00+ mm, otherwise it's in the 8.00+ mm line.

Last of the three factors that affect the measurement of an object tells us that no measuring device can be so accurate. Hence, those two kinds of calipers we used, also have their own margin of error. The Vernier caliper has an error of ± 0.02 mm, while the micrometer has ± 0.01 mm. It means that micrometer is more accurate compared to  the Vernier by 0.01mm, which is kinda big difference. 

I think the average length of the rice grain is the data of an international research which says that length of the rice grain is 7.09± 0.36 mm. This, I believe, is true because they have measured a lot of rice grain. Our professor said that they were able to measure a thousand rice grain.A matter of 950 grain-difference to our data. So obviously, they got a wider gathering of data, and a more acceptable mean. I think the next question may be: What is the variant of rice they measured?

Activity 1: On Measurement

Last Monday, we discussed about measurements. I think every laboratory class has to allot time for simple discussion regarding measurement. Especially, this is a Physics lab course, so measurement is a part and parcel of every topic. Well, I've learned new things and few techniques which is actually handy for laboratory class. I guess I'll mention my favorites of those. First is that measurement units are products of arbitration, that no measurement is literally exact. It kinda struck me, though. Second, is that all the measurements are based on the judgement of the person, like if you see a reading between 1 and 2 mm., most people  would probably bet that reading is exactly 1.5 mm regardless of many considerable yet small decimal values. And last, the limitations of the device you're using affect your measurement.

Activity 2: Using Calipers

So this is the activity that we will finally apply and get to see what the results would be like... We're going to measure the length of a rice grain. Sounds simple. But personally it's a no. Honestly because, back when I was in high school, I've never touched or seen this:

A Vernier caliper. (image from amazonsupply.com)

and even this:

                                                 A micrometer caliper.  (image from amazonsupply.com)

 So apparently, that was my first time to use laboratory apparatus like these. Although, we did not have enough time to the micrometer for this meeting..  Okay I'm going to tell how our group measured the rice grain. At first, we were warned by our instructor using the Vernier caliper. He said that you must check the measurement readings by holding the caliper upright because a little parallax could cause you a big trouble while measuring. I tried it myself, reading the measurement slightly slanted and it is true! 

Then, we measured the rice grain one by one, piece by piece. It's kind of hard because whenever it's my turn to measure the grain, my thumb and index finger got stuck as well. We set our goal to 50 grains but then our group ended up measuring only 43 grains. One thing I noticed from our results is that all our measurements (in mm.) are relatively close to each other. If I remembered our data right, we only had 2 out of 43 readings containing 6.00+ mm. The rest mostly measured as 7.00 + mm. .Our instructor also shared the results from a research about the average length of rice grain from a high-resolution experiment. He said that those researchers were able to measure at least a thousand grains of rice. Woah, they were so patient!

Overall the two activities, I think, train us to be careful or meticulous about the objects we want to measure.... and be patient, of course. It's hard to measure a grain of rice, especially if you're trying to measure a thousand of them!