What Is Torque?

Torque is defined as the measure of the force that can cause an object to rotate on an axis. Most commonly, people hear this term used when talking about cars. Cars utilize torque to turn the wheels to propel the vehicle forward. 

Measuring Torque

Torque, typically measured in pounds per foot (Ft/lbs) or newtons per meter (Nm), possesses both magnitude and direction. This classifies it as a vector quantity.  The direction of the vector depends on the direction of the force on the axis. When opening a door, a users applies force to the side of the door farthest from the hinges. Pushing on the side of the door closest to the hinges requires much more force.  Even though the work remains the same in both scenarios, one would generally prefer to apply less force, ergo the typical location of a door handle.

Multiplication of force and distance results in torque calculation. As a vector quantity, it can be tricky to understand at first. Because these calculations involve a vector product, the “right-hand rule” applies. Take your right hand and curl the fingers of your hand in the direction of rotation caused by the force. Your thumb of your right hand now points the direction of the vector.

Static or Dynamic?

When discussing torque there are two types: static and dynamic. The static variety does not produce an angular acceleration. When pushing on a closed door, static torque is being applied because the door is not swinging on its hinges. A bicycle being peddled at a constant speed is classified as static because it is not accelerating.

Your vehicle’s torque, as discussed earlier, is a dynamic form due to its production of an angular acceleration of the wheels at an increased rate of speed. Power tools (pneumatic wrenches, etc.) typically apply dynamic torque.

Everyday Science

There are many reasons we use these measurements in our daily world. For example, when a manufacturer makes a nut and bolt, they define that bolt’s maximum torque value. You use a torque wrench to ensure you tighten that nut down to that exact specification to prevent failure of the nut and bolt. You want to make sure it’s tight, but not too tight! This can make the difference between your car’s wheels rolling down the road for eight thousand miles … or eight minutes.

What Is A Pipette?

A simple, critical, instrument in labs across the world, a pipette transports a measured volume of liquid safely and accurately.  Pipettes can be as simple as plastic tubes and as complex as precise electronic devices.  They generally have a single channel, eight (8) channels, or twelve (12) channels. Dr. Heinrich Schnitger, from Marburg, Germany, invented the first micropipette in 1957. This model measured and transported a fixed amount.

Later, the co-founder of biotechnology company Eppendorf, Dr. Heinrich Netheler, inherited the rights and initiated the global and general use of micropipettes in labs. In 1972, Warren Gilson and Henry Lardy, of Wisconsin, developed the first adjustable micropipette. Micropipettes dispense between one (1) and one thousand (1000) μl (microliters), while macropipettes dispense greater volume.  Most pipettes work by creating a partial vacuum above the liquid-holding chamber, or the tip, and selectively releasing this vacuum to draw up and dispense liquid.

The Air Displacement Pipette

Air displacement micropipettes deliver a measured volume of liquid, depending on size. Additionally, they require disposable tips that come in contact with the fluid and operate using a piston-driven air displacement. The vertical movement of a metal or ceramic piston within an airtight tube creates a vacuum. The pipetting liquid around the tip moves into the vacuum and can then be moved and dispensed as needed.

These pipettes have the capability of precise and accurate measurement, but since they rely on air displacement, changing environmental conditions, especially air temperature and user technique, can introduce inaccuracy.  Because of this, such equipment requires regular maintenance and calibration.  End users should receive training to properly use correct and consistent technique.

The Positive Displacement Pipette

Similar in function to air displacement pipettes, positive displacement pipettes see less common use. Generally, users deploy these pipettes to avoid contamination and to handle volatile or viscous substances, or extremely small volumes, like DNA.  The main difference comes in the disposable tip, a microsyringe made up of a capillary and a piston which directly displaces the liquid.

Air displacement pipettes use disposable tips that contact the liquid to be measured and transported.

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Air displacement pipettes use disposable tips that contact the liquid to be measured and transported.

Other Varieties

Volumetric pipettes, otherwise known as bulb pipettes, have a large bulb with a long narrow portion above a single graduation mark. This mark serves as the calibration point for a single volume, similar to a volumetric flask.

A single piece of plastic forms transfer pipettes, also known as beral pipettes. In beral pipettes, the bulb sometimes serves as the liquid holding vessel.

Electronic pipettes were developed to improve ergonomics of pipettes by reducing the necessary force to operate them. A small electric motor powered by an internal battery replaces manual piston movement.  Where manual pipettes require a movement of the thumb, electronic pipettes operate by the push of a button.  Users employ a digital display on the unit to program settings such as volume.

Modern advancements in science and technology changed the look and operation of pipettes over the years, but not their main purposes. Pipettes, to this day, move a liquid from one place to another accurately and safely.

What Is Metrology?

Per Merriam-Webster’s online dictionary, metrology is “the science of weights and measures or of measurement.” [1] It can also refer to a system of weights and measures. [1]

Definitions are helpful, but application is more meaningful. Why are measurements so important? How does standardization work? What purpose does it serve in the real world applications of science, business, finance, and technology?

The Importance of Metrology

Metrology is important for several reasons:

• Knowledge must be shared. [2] Without common measures, an event cannot be described and documented so that independent, unbiased observers can reproduce that event.
• Measurements protect us. [2] From medication dosing to highway speed limits, numbers matter. Having a standardized number as a target, as well as having a standard measure for that target, protects the common well-being and potentially saves lives.
• Contracts and transactions must have numbers as a foundation. [2] Everything from food portions to gas pump prices is affected by many measures. Without numbers, acceptable (and unacceptable) performance cannot be described and determined.
• Measurements strengthen competition. [2] Once an industry knows both legal and customer requirements, they can analyze and determine how closely those are met. Then they can innovate and remain competitive by better meeting requirements.

Metrology in Operation

Obviously, having standard numbers is critical. But how is that achieved? How does society identify measures and implement them as standards?

First, it is critical to identify the what must be measured and the best measures to use. [3] Next, collaborate to generate approval for and acceptance of the measure. [3] Finally, codify how to use the measure [3] so others can use it.

Metrology in the Real World

Within metrology, there are three subfields:

• Legal: This subfield focuses on numbers used in legal or legislative efforts. The documented measures may protect personal health, improve public safety, increase environmental protection, or ensure fair trade on behalf of consumers. [3,4] The numbers in these efforts help develop and enforce fair rules for all.
• Applied or Industrial: People in this subfield concern themselves with numbers used to manufacture goods or to produce and refine natural materials. Once the numbers are established, people in this subfield also ensure proper calibration of instruments used to obtain numbers in the manufacture of goods or production of materials. [3,4]
• Scientific or Fundamental: Focus on scientific metrology allows the establishment of new units of measure and the development of methods for repeatedly obtaining measurements in the new unit. Those in this field gain community support for new measures and methods of measurement and teach general users how to use the measures and related methods. [3,4]

Final Thoughts

Throughout history, man has looked for ways to measure what he produces and its value. As early as 1875, a global need for standardized measurements was recognized. [5] However, the standards vary from industry to industry. The science of measurement and related standards continues to grow in need and popularity.

Citations

[1] https://www.merriam-webster.com/dictionary/metrology, last visited 12/21/2017
[2] http://www.french-metrology.com/en/history/interest-metrology.asp, last visited 12/21/2017
[3] https://en.wikipedia.org/wiki/Metrology, last visited 12/21/2017
[4] http://www.brighthubengineering.com/manufacturing-technology/63936-what-is-metrology/, last visited 12/21/2017
[5] http://worldmetrologyday.org/faq.html, last visited 12/27/2017
[6] https://digitalcollections.nypl.org/items/510d47db-bfd3-a3d9-e040-e00a18064a99, last visitied 12/27/2017