By MICHAEL JOHN UGLO
GOOD day all our avid readers of Science and Technology. We will now commencea new series on Science in Action today.
In the coming lectures, we will try to be as brief as possible. Out topic for today is Measurement. In Grades 11 and 12 physics and advanced mathematics in Papua New Guinea secondary schools, national high schools and Flexible Open and Distance Education (Fode), the very first unit taught and studied is measurements
These lectures will provide the much-needed pivotal grounding into this field of science, technology and engineering that PNG will find indispensable.
Therefore, in all our Science in Action lectures starting from today, we will discuss in detail the thinking and belief systems in all the science (physics, chemistry, biology and geology) topics taught in PNG school and also as applied in the modern technological world. If you are a student or a teacher, this will be good additional reading for you lecture until we complete the entire science curriculum of PNG.
What measurement is
Measurement may seem a somewhat obsolete term. It is true. Measurement in essence, is a way to state accurately about an object or an event. People in the past used all sorts of things to measure objects or events. This has been practiced in England, United States, China, Greece, India, Australia and virtually everywhere. Most of the modern inventions have been based on measurements and calculations such as the idea of electricity and its principles.
When James Clerk Maxwell laid the foundation for electricity and magnetism, he corrected many works and axioms in his time to come up with relevant equations that calculated the speed of the radiations and that led to the accurate calculation of the speed of light as 3 x 108 meters per second.
The attempt to measure was initially to avoid fraud in commerce. It has to state a specific quantity for trade and that has to be a fixed quantity. Given the many ways of measurement, there was a need to come up with an internationally agreed and recognised mode of units and that was done in the 1960s. That international standard system was called the International Systems of measurement, abbreviated as the SI metric system.
There are seven fundamental metric system units that have been identified. These are the units and quantities with their symbols, namely kilogram (kg) for mass(m), candela(cd) for light intensity or luminosity, mole (M) for amount of substance, seconds (s) for time (t), meter for length (L) and Kelvin (K) for temperature(T). There is no artefact attached to any of these units as a medium of reference except only one and that is the mass in kilograms. There is a sample near Paris in France that has an artefact of this mass.
All the quantities and units can be combined and derived from one another except the amount of substance which is measured in moles. All the other units are derived from the above seven fundamental units.
For instance, to find the density of an object, you can divide mass by volume. The formula is Density (D) equals (=) mass (Mass) over (/) volume (V) , (D =M/V). This will have the following; Density (kgm-3) = Mass (kg)/volume (m3).
As we are sorting out quantities and their appropriate units, it is very important in physics and mathematics that the respective units and quantities are included as needed. If those units, for instance, are not included then your answer can be marked wrong. For instance, if the speed of a vehicle is to be determined, you have to write meters per second or m/s or ms-1 beside the answer. That is, if the speedometer of a vehicle is read 4.8km, then the speed is 4.8 km/s. Do not just write 4.8 or 4.8km for an answer because that is not correct.
Furthermore, in physics and maths the units can be cancelled form their divisor and dividend positions to give the final correct answer. For instance, if you have as your numerator 9kms-1 m-3 /3m-3s-1 then, your final answer will be 3km. That is all the other units are cancelled out and that is 9kms-1 m-3 /3m-3s-1. The final answer is 3km.
Quantities can be increased and decreased with the correct amounts when required. For instance, you can convert meters to the smaller units of centimetres, millimetres or even micrometres or nanometres by multiplying with their respective multiplying factors which are 100cm, 1000mm, 1000,000 (106) µm. 109nm . You can also convert metres to bigger units like kilometres by dividing using its appropriate dividing factor which is 1000.
Measurement is used to relate one quantity and event to or from another. To relate this accurately we have to have a standard medium in which this particular quantity will be very atomic or central without any bias and can take as our point of reference.
There were several reference points derived for the seven fundamental units discussed above. These are respectively kilogram (kg) for Planck’s constant h, candela(Kcd) for luminous efficacy of a 540 terra hertz (540THz), mole (M) for Avogadro Constant NA, seconds (s) for hyperfine splitting in caesium -133, meter(m) for speed of light c, and Kelvin (K) for Boltzmann constant k.
Errors result as we deviate from trying to get close to the actual answer as much as possible. There are errors such as reaction time error, parallax error and zero error. Reaction time error happens when one misses out in getting as close as possible to the starting time. Parallax error is when one does not place the eye-sight at right angle or perpendicular to the instrument as possible to get the correct reading. Some call this type of error motion errors or movement errors. Zero error is when one is counting or taking measurements, it is not started at zero as a starting point. Always at whatever point when starting to take readings, it has to be started with zero.
My prayer for PNG today is: “The love I bear, is held from no one. All I own and all I do, I give to you,” says the Lord.
Next week: Kinematics in science and technology
nMichael Uglo is the author of the science textbook “Science in PNG, Pacific, Asia & Caribbean”, and a lecturer in avionics, auto- piloting and aircraft engineering. Please send comments to: [email protected]