Measurement and Units
What do we mean by units and why is measurement important? Are they connected? If yes, How? And why is it important to measure at all? A very fundamental set of questions, get raised in our minds as we grow. As a toddler when one asks for more candies or ice cream from parents, they realize it is time to start teaching the counting, using such an opportunity to their child. For a child numbers and every human being, they form the root of mathematics, which leads to units and measurements viz., from an abstract thing to a physical entity. One can never find a child being taught numbers without the aid of pictures of fruits, flowers, animals, etc. The reason, concept of numbers is abstract and the mind of a toddler is not yet grown enough to convert an abstract thing into a physical entity.
A child does not know of “One, Two, Three, etc.”! It is only by seducing the child with candies or by pictures of fruits, flowers, pets, etc., that the abstractness of the numbers is replaced by making the child connect the dots physically. It is only after this a child enters into the world of physical measurements; with which he/she then deals all its life. But units are still a far-off concept.
Once the child starts recognizing numbers, he/she is then taught to say measure the length of their room by using their steps. So, in the end, if their room length say takes their 10 steps to get traversed, now they can be told the concept of unit. Meaning the length of their room is “10 steps” of their own. So, the unit here is “STEP”, otherwise saying just 10 will make no sense unless 10 steps are stated together! In other words, separating the unit from measurements carried out will not make any logical sense.
But still how and why measurement and units should be linked remains a puzzle for a growing child. This puzzle gets solved once the child recognizes the consumption of milk or fruit juice which he/she is asked to consume in breakfast before going to his/her school. The amount (measurement like in the case of the length of their room) of milk or juice they consume can at the start be described as One Glass. So, the quantity of milk/juice gets the unit of One Glass or more if the child consumes that many. But unlike the length which did not weigh but the glass of milk/juice does have weight. Hence, measurement of weight should have a unit itself, which here is “GLASS”! Is that a correct way to describe the quantity of liquid consumed, which is milk or juice in this case?
So, between fruits, candies, milk, and juice as physical entities, we found there is a primary difference viz., of one being solids and the other liquids. There is one more, which is the air we breathe and it is a form of gas as a physical entity. We will talk about all these and their ways to measure and units in days to come.
Interestingly, in Physics, the primary set of dimensions that we are concerned with are Mass (M), Length (L), and Time (T). And all measurements can be converted into these dimensionless quantities as MLT, which we will see while progressing to simplify the complexity of Physics as we go.
For further details read Halliday & Resnick’s Fundamentals of Physics.
March 26, 2021