# How to Use a Mass Measurement Scale

Mass is a property of matter. It doesn’t change with changes in shape or position. It’s the same on Earth, on Jupiter or in space.

It is important to understand the difference between mass and weight. Many people use these terms interchangeably but it is a mistake. Mass is a fundamental physical property and weight is only a measure of how an object interacts with gravity.

## Definition

Mass is a measure of the amount of matter an object contains, and it is measured in kilograms and related units. Weight, on the other hand, is a measurement of the force exerted on an object by gravity on Earth, and would be different if you were standing on another planet.

In physics, mass is also the quantitative measure of an object’s inertia – the resistance it offers to acceleration (change of velocity) when a force is applied. Thus, objects of the same mass have the same inertia and the same acceleration under identical conditions.

When using SI units, the word “mass” is used rather than the term “weight.” However, many people still use the term weight to refer to an object’s inertia and the force of gravity acting on it. This is confusing, and the terms should be distinguished as described below. The meter and the kilogram are two of the seven base units of the International System of Units (SI). Countries that subscribe to the metric convention were given copies of the international standard artefacts – a copper prototype of the metre, and a platinum-iridium International Prototype Kilogram – which they maintain, known as National Prototype Metres and National Prototype Kilograms. These are compared against the international standard at regular intervals.

## Units

The SI comprises a coherent system of seven base units: the second (s, unit of time), metre (m, length), kilogram (kg, mass), ampere (A, electric current), kelvin (K, thermodynamic temperature), candela (cd, luminous intensity) and mole (mol, amount of substance). It can also accommodate coherent derived units, which are obtained as products or ratios of base units.

For most of the base units the BIPM publishes a mises en pratique, or “realisations” — in other words, the best practical realisations currently available. This separation of the defining constants from the definitions means that improved realisations can be developed as science and technology advances, without needing to redefine the underlying units.

The kilogram is the only one of the base units to be defined by a physical artefact; its physical properties are constantly changing, so international scientists have been urging a redefinition based on some other invariant property. Two possibilities have attracted particular attention: the Planck constant and the Avogadro constant.

## Examples

In order to measure mass, you need a balance scale. Put the object you want to weigh on one side of the scale and add weights or other objects that have the same amount of matter to the other side. The amount of weight needed to counter the force of gravity is the object’s mass.

Alternatively, you can use an electronic mass measurement device. These devices have sensors that can detect the movement of atoms or molecules, which can then give an estimate of an object’s mass.

While it might be tempting to confuse weight and mass, it is important to know that they are two different measurements. Objects may be weightless on the moon due to lack of gravity, but that doesn’t mean they don’t have mass. For example, a rock may have the same mass on the moon as it does on Earth. However, the moon is much smaller than Earth, so it would take less weight to equal the same amount of matter on the moon.

## Applications

A balance or scale is one of the most common instruments used to measure mass in a science laboratory. A high-precision scale calibrated with stainless steel standards translates the force exerted on an object by gravity into its conventional mass (true mass minus 150 ppm of buoyancy).

The same technique can be used for single-molecule mass measurements. By measuring the frequency at which ions are emitted from an Orbitrap instrument, a software program plots what Thermo calls selective temporal overview of resonant ions (STORI) data.

Benesch, for example, uses this information to study assemblies made between molecular chaperones and the proteins they protect in cells. He wants to know whether these structures prevent the formation of amyloid fibers, a protein aggregate that’s associated with eye problems and other diseases. Using mass photometry, he can see whether a complex has assembled properly or clumped together into a glob of debris. Having this information can save time and effort, because researchers can immediately filter out samples that aren’t suitable for other structural biology methods.

# Importance of Quality in the Weighing Process

Good laboratory practices and quality weighing equipment are critical for accurate mass measurements. Errors can occur due to a number of factors.

Whether you’re a chef perfecting a recipe or a healthcare professional ensuring patient safety, precise weighing is key. This article will cover the steps necessary to accurately conduct a weighing process.

## Weight Measurement

Weighing is the process of measuring an object or substance’s weight, which is a measure of its force due to gravity. The term “weight” is also used to describe an individual’s body mass, which is the total amount of matter in their body.

A spring scale measures an object’s weight by observing how far the object pushes a spring. This is different from a balance scale, which compares the force exerted on an object to a standard reference weight.

A weighing system’s accuracy depends on the quality of its components. It’s essential that the load cell—also known as a sensor or transducer—can support the entire load to be measured. The load cells send a signal proportional to the load through a junction box and to a weight controller. The weight controller converts the signal into a readout on a display or digital panel. The junction box and weight controller must be located away from the load to avoid interference from vibrations, pulsations and other forces.

## Calibration

Scales that are used for more complex tasks or in higher sensitivity applications may require specialist calibration. This includes pharmaceutical, aerospace, and manufacturing scales as well as hanging scales, industrial and truck scales and other larger scale equipment. LotusWorks offers a tailored balance calibration service using mobile teams and an ISO 17025 2017 accredited laboratory.

Calibration is the process of testing a weighing instrument to establish a relationship between the measurement technique and known values. This teaches the instrument to provide more accurate results when samples of unknown value are tested.

It is essential to select the correct calibration weights and perform a few pre-tests before starting the full calibration process. Ensure the calibration environment is stable and free from drafts, vibrations or temperature fluctuations. Lastly, it is important to tare the weighing instrument with an empty weighing pan to set the display to zero. Depending on the calibration procedure, the scale will then be tested with increasing and decreasing test loads.

## Traceability

Traceability relates to the fact that a measurement can be traced back to a defined standard. This is a key element in the overall quality of your weighing process.

The National Institute of Standards and Technology (NIST) is the keeper of the ultimate definition of a pound, as well as other measurement units like inches, seconds and volts. They ensure that every scale has an unbroken chain of calibrations to the underlying standard, giving you confidence in your results.

When weighed materials are processed, they can be subject to many contaminants that may be introduced during handling and transfer. Adding a small amount of water to your weighing container helps dissolve and loosen any remaining solids or other liquids that are trapped in the container, making for a cleaner process. In addition, this practice promotes lean manufacturing and continuous improvement. It can also help prevent costly product recalls.

## Automation

Weighing automation is a crucial step to achieving efficient, reliable, and cost-effective production. However, this does not negate the need for human oversight. Rather, it allows you to shift your workforce to duties that require more hands-on attention.

Precise weighing ensures the order of ingredients in a mixture, maintaining product consistency and quality. This is especially important for food and pharmaceutical manufacturing where errors could be costly.

Streamlined inventory management helps reduce unnecessary expenses by providing instant access to information about products and their origins, as well as previous weighment records. This enables you to track inventory and detect any potential problems, such as under- or over-loading trucks.

Smart weighing systems are integrated into industrial automation networks using a protocol known as Industrial Ethernet (IE). This makes it easy to transfer time-critical and deterministic process control data, as well as business intelligence data between OT and IT systems. This enables you to optimize your overall production and make faster decisions about your business operations.