In a metric system, units get larger or smaller by powers of 10. A meter is a lot bigger than a yardstick and a kilogram is 1,000 times heavier than a paperclip.
It’s important to understand the difference between weight and mass. Kids are naturally inquisitive, and introducing them to this concept early will help them effortlessly grasp more complex concepts in subjects like physics later on.
Units
Throughout history, people have used a variety of methods to measure what is commonly known as weight. However, in 1875 at the International Metric Convention, scientists created an international prototype kilogram and defined it as the base unit for mass measurement. This made it part of what is called the metric system, with the SI prefix “kilo” attached to its name and symbol for convenience.
Many non-SI units are still widely used, including the kilogram and its multiples and fractions. They are called derived units because they are products and ratios of the fundamental, or base, SI units. Unlike the fundamental SI units, they do not have their defining constants separated from their definitions; therefore, these can change as science advances without having to redefine them. This makes them less ideal than the SI base units, which have their defining constants explicitly separated from their realisations in order to allow for improvements in measurements without having to rewrite the units’ definitions.
Calibration
Calibration is the comparison of an instrument’s measurement value with that of a calibration standard. The standard could be another measurement device, a physical artifact like a scale or ruler, or it could be an electronic signal, such as a temperature, electrical current, sound wave or voltage. The calibration standards used in a calibration must be of known accuracy. This is called “traceability.”
Calibrated devices improve efficiency, compliance and safety in business operations, minimizing waste, downtime and safety hazards. It also helps companies meet regulatory requirements and quality industry standards, and provides better insight into processes and products for greater competitiveness.
Thousands of calibrations are performed every day throughout the world to keep our lives working properly. From the weight of our luggage on an airplane to a blood pressure reading from your doctor, you benefit from calibration every time you use a device that relies on accurate measurements. Without a globally agreed upon system of measurement, our lives would not be possible as we know it.
Scales
Weighing instruments, also known as scales or weight scales, come in a wide range of capacities and readabilities. They are used in industrial, agricultural and commercial applications as well as for home use and at the supermarket.
In its most traditional form, a balance (also called a beam or mass balance) determines mass by comparing an unknown mass with one of standard masses on a pair of equal-arm plates – think of a see-saw. The unknown mass is suspended from one plate while the other plate supports a counterweight. When mechanical equilibrium is achieved the plates or bowls are at neutral rest.
Many modern scales display your apparent weight in pounds, but if you were to step onto a scale on the moon or another planet, that would change the value because gravity differs across the globe and even within a city. The good news is that standardized measurements such as kilograms facilitate international trade and allow for quick comparison between products and services.
Experiments
Exact mass measurements are required for nuclear physics and astrophysics. For these applications, a precise atomic mass table is indispensable. This requires a large number of experimental data to be collected and evaluated. For this purpose, an atomic mass evaluation (AME) is regularly published [18].
The accuracy of an exact mass measurement depends on how close the measured peak is to its reference. The maximum separation of masses is defined by the resolution of a mass photometry measurement, which in turn depends on the concentrations of different species in the sample. Using an ion trap, the separation can be enhanced to tens of micromolar.
A technique that uses the time-of-flight of stored ions in an isochronous magnetic field allows the precision to be increased even further. This is achieved by measuring the cyclotron frequency of the ions in a multi-reflection time-of-flight measurement system, for example, in an ion storage trap. This method allows the mass of complex molecules to be measured with a high resolution.