Most second-year university engineering students can easily explain the differences between force, torque and pressure. The reason for their confident answers is that engineering schools typically require a term of study in both static and dynamic forces by a students sophomore year. However, from that point on, further studies in these areas are usually confined to aerospace, civil and mechanical engineering disciplines. Few electronic engineers need or will take advanced force mechanic courses.
But modern advances in material properties and device miniaturization as in micro-electro-mechanical systems (MEMS) and sensors mean that force, torque and pressure are relevant across all of the major disciplines. A quick technical review will help remind everyone of these basic concepts.
Force
Simply put, a force is a push or a pull upon an object. A force can cause an object with mass to change its velocity, i.e., to accelerate. Since a force has both magnitude and direction, it is a vector quantity.
A unit of force in the International Systems (or SI) of units is a newton. One newton is defined as the unit of force which would give to a mass of one kilogram an acceleration of 1 meter per second, per second. In terms of an equation, force equals mass times acceleration (F = ma).
Actually, Newtons Second Law of Motion defines force as the change in momentum over time, not mass through an acceleration. But the momentum equation is reduced to F=ma for basic engineering calculations.
Sometimes the word load is used instead of force. Civil and mechanical engineers tend to make calculations based on the load in which a system (e.g., a bridge) is resisting the force of gravity from both the weight of the bridge as well as the vehicles driving over it.
Newtons Laws have been called the basis for space flight. According to NASA, understanding how space travel is possible requires an understanding of the concept of mass, force, and acceleration as described in Newtons Three Laws of Motion. Consider a space rocket in which the pressure created by the controlled explosion inside the rocket's engines results in a tremendous force known as thrust. The gas from the explosion escapes through the engines nozzles which propels the rocket in the opposite direction (Law #3), thus following F=MA (Law #2) which lifts the rocket into space. Assuming the rocket travels beyond Earths atmosphere, it will continue to move into space even after the propellant gas is gone (Law #1).
Newtons Three Laws of Motion
1.
Every object in a state of uniform motion will remain in that state of motion unless an external force acts on it.
2.
Force equals mass times acceleration [F = ma]
3.
For every action there is an equal and opposite reaction.
Torque
The first university course in static forces is usually followed by a course in dynamic forces in which the idea of rational force or torque is introduced. Torque is the tendency of a force to rotate or twist an object about an axis, fulcrum, or pivot. It is the rotational equivalent of linear force.
Formally, torque (or the moment of force) is the product of the magnitude of the force and the perpendicular distance of the line of action of force from the axis of rotation. The SI unit for torque is the newton metre (Nm).
Image Source: Wikipedia by Yawe (Public Domain)
Deriving the equation for torque is often done from a purely force perspective. But it can also be accomplished by looking at the amount of work required to rotate an object. This was the approach the Richard Feynman used in one of his lectures on rotation in two-dimensions.
We shall get to the theory of torques quantitatively by studying theworkdone in turning an object, for one very nice way of defining a force is to say how much work it does when it acts through a given displacement, explained Feynman.
Feynman was able to show that, just as force times distance is work, torque times angle equals work. This point is highlighted in several avionic and aeronautical examples from NASAs Glenn Research Center where NASA designs and develops technologies for aeronautics and space exploration. Force, torque and pressure concepts continue to exert their influences far beyond the earths atmosphere. Concern the release of a large satellite like the Cygnus Cargo Craft from the International Space Station (ISS). The satellite is connected to a large robotic arm that removes it from the ISS prior to release into space. The robotic arm acts just like a huge moment of force in space subject to forces, torques and pressure acting in space.
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Many of us are familiar with gauge pressure from measuring tire pressures. Gage pressure is the pressure relative to the local atmospheric or ambient pressure. This is in contrast to absolute pressure or the actual value of the pressure at any point. This will make more sense shortly.
Pressure is the amount of force acting per unit area. The SI unit for pressure is the pascal (Pa), equal to one newton per square meter (N/m2). Pressure is also measured in non-SI units such as bar and psi.
In his lecture on the The Kinetic Theory of Gases, Feynman introduced the concept of pressure by thinking about the force needed for a piston plunger to contain a certain volume of gas inside a box. The amount of force needed to keep a plunger or lid of area A would be a measure of the force per unit area of pressure. In other words, pressure is equal to the force that must be applied on a piston, divided by the area of the piston (P = F/A).
Applications for pressure technologies exist both on and off the planet. In space, however, pressure is so low that it may almost be considered as non-existent. Thats why engineers often talk about vacuum rather than pressure in space applications. A vacuum is any pressure less than the local atmospheric pressure. It is defined as the difference between the local atmospheric pressure and the point of a measurement.
While space has a very low pressure, it is not a perfect vacuum. It is an approximation, a place where the gaseous pressure is much, MUCH less than the Earths atmospheric pressure.
The extremely low pressure in the vacuum of space is why humans need space suits to provide a pressurized environment. A space suit provides air pressure to keep the fluids in our body in a liquid state, i.e., to prevent our bodily fluids from boiling due to low pressure (via PV = nRT). Like a tire, a space suit is essentially an inflated balloon that is restricted by some rubberized fabric.
Homework question: Why didnt the wheels on the Space Shuttle bust while in space, i.e., in the presence of a vacuum? Look for the answer in the comments section.
In summary, force, torque, pressure and vacuum are important physical concepts that thanks to advances in material sciences and MEMS devices cross all of the major disciplines. Further, these fundamental concepts continue to have relevance in applications like space systems among many others.
Continue reading here:
Tutorial: What are the differences between force, torque, pressure and vacuum? - DesignNews
- A Q&A with Katya Echazarreta, the first Mexican-born woman to travel to space - Astronomy Magazine - April 24th, 2024 [April 24th, 2024]
- Japans planning its first lunar steps with the Artemis program - The Hill - April 24th, 2024 [April 24th, 2024]
- DC Eyes Beijing's Investments In Space - Payload - Payload - April 24th, 2024 [April 24th, 2024]
- THIS WEEK @NASA: More Partners in Space Exploration, Upgrade to Testing Facilities for Artemis II - SpaceCoastDaily.com - April 24th, 2024 [April 24th, 2024]
- Explore Space and Poetry with NASA and Poet Laureate Ada Limn - sxsw.com - April 24th, 2024 [April 24th, 2024]
- NASA warns of secret military presence in space disguised as civilian programs - TweakTown - April 24th, 2024 [April 24th, 2024]
- NEW: UAH wins first place in college division in NASA's 30th Human Exploration Rover Challenge - Hville Blast - April 24th, 2024 [April 24th, 2024]
- Are we prepared for Chinese preeminence on the moon and Mars? (op-ed) - Space.com - April 24th, 2024 [April 24th, 2024]
- As space exploration increases, effective space regulation is a necessity - Verdict - April 24th, 2024 [April 24th, 2024]
- NASA Announces Winners of Power to Explore Challenge - NASA - April 24th, 2024 [April 24th, 2024]
- NASA tests walking robot on Mount Hood for space exploration with universities - KTVL - April 24th, 2024 [April 24th, 2024]
- Five future astronauts certified from European Space Agency's 2022 graduating class - UPI News - April 24th, 2024 [April 24th, 2024]
- Sweden becomes 38th country to sign NASA's Artemis Accords for moon exploration - Space.com - April 24th, 2024 [April 24th, 2024]
- Space start-up claims to have discovered propellant-free propulsion system - NewsBytes - April 24th, 2024 [April 24th, 2024]
- Soyuz Spacecraft Launches to Space Station With NASA Astronaut - SciTechDaily - March 24th, 2024 [March 24th, 2024]
- This Week In Space podcast: Episode 103 Starship's Orbital Feat - Space.com - March 24th, 2024 [March 24th, 2024]
- From 3D To Outer Space: Register For WCC Youth Summer Camps - mitechnews.com - March 24th, 2024 [March 24th, 2024]
- NASA and SpaceX: Enhancing Space Exploration with the 30th Resupply Mission - Space Daily - March 24th, 2024 [March 24th, 2024]
- The Cosmic Enigma: How Space Exploration is Unraveling the Universe's Birth Secrets - yTech - March 24th, 2024 [March 24th, 2024]
- Following Safe Return, NASA's SpaceX Crew-7 to Recount Space Mission - NASA - March 24th, 2024 [March 24th, 2024]
- The Heat: Space Exploration - CGTN America - March 24th, 2024 [March 24th, 2024]
- SpaceX Time-Lapse Video Captures the Essence of Space Travel - yTech - March 24th, 2024 [March 24th, 2024]
- TOP 4 Reasons to Return to the Moon - The Universe. Space. Tech - March 24th, 2024 [March 24th, 2024]
- SpaceX Dragon Successfully Attaches to ISS Bringing Vital Research Payloads - yTech - March 24th, 2024 [March 24th, 2024]
- End of an Era: Delta IV Heavy Makes Final Journey to the Stars - yTech - March 24th, 2024 [March 24th, 2024]
- Photography exhibition at the Mound delves into space exploration - The National - March 24th, 2024 [March 24th, 2024]
- Lunar Node 1: the trailblazing lunar beacon guiding NASA's future in space exploration - Boing Boing - March 24th, 2024 [March 24th, 2024]
- SpaceX's CRS-30 Mission: Delivering Innovations and Research to the ISS - yTech - March 24th, 2024 [March 24th, 2024]
- Remembering Tom Stafford, the Space Races Peacemaker (1930-2024) - AmericaSpace - March 24th, 2024 [March 24th, 2024]
- 9 Hints That Kingdom Of The Planet Of The Apes Involves Space Travel - Screen Rant - March 24th, 2024 [March 24th, 2024]
- NASA sends science projects and hardware aboard SpaceX's 30th resupply launch to ISS SatNews - SatNews - March 24th, 2024 [March 24th, 2024]
- SpaceX Dragon Spacecraft Docks to Space Station With New Science and Supplies - SciTechDaily - March 24th, 2024 [March 24th, 2024]
- Moon Race 2.0: Why so many nations and private companies are aiming for lunar landings - BBC.com - February 16th, 2024 [February 16th, 2024]
- NASA Selects Texas A&M As First Approved Exploration Park Facility - Texas A&M University Today - February 16th, 2024 [February 16th, 2024]
- The Space Economy in 2024 - OODA Loop - February 16th, 2024 [February 16th, 2024]
- Opinion | It's an exciting time in space exploration. But U.S. leadership is at risk. - The Washington Post - February 16th, 2024 [February 16th, 2024]
- NASA Experiment With Fire in Space Ends When Entire Spacecraft Burns Up - Futurism - February 16th, 2024 [February 16th, 2024]
- NASA Selects Texas A&M as First Approved Exploration Park Facility - NASA - February 16th, 2024 [February 16th, 2024]
- Ground-Based Lasers Could Accelerate Spacecraft to Other Stars - Universe Today - February 16th, 2024 [February 16th, 2024]
- 8 Space Exploration Books to Add to Your TBR - Book Riot - February 16th, 2024 [February 16th, 2024]
- Meet the Elected Members of the African Space Council - Space in Africa - February 16th, 2024 [February 16th, 2024]
- NASA working with Texas A&M to build new spaceflight research facilities - 25 News KXXV and KRHD - February 16th, 2024 [February 16th, 2024]
- Inflatable Habitats: Expanding Space Exploration - Lockheed Martin - February 16th, 2024 [February 16th, 2024]
- China's Rising Ambitions in Space Exploration: Chang'e Missions and International Cooperation - Medriva - February 16th, 2024 [February 16th, 2024]
- Pressured Space Exploration in Today's Era - Mirage News - February 16th, 2024 [February 16th, 2024]
- Exoplanet Hunter Sets Its Sights on Jupiter: A New Twist in Space Exploration - SciTechDaily - February 16th, 2024 [February 16th, 2024]
- Frontier Aerospace TALOS Engines Used For Space Exploration - PR Newswire - February 16th, 2024 [February 16th, 2024]
- Exploring the Potential of Minimoons - Medriva - February 16th, 2024 [February 16th, 2024]
- Understanding the Role of TRISH in Space Health and its Future Innovations - Medriva - February 16th, 2024 [February 16th, 2024]
- The Future of Satellite Refueling and In-Orbit Servicing - Medriva - February 16th, 2024 [February 16th, 2024]
- Japan makes third attempt to launch next-gen rocket - Yahoo Singapore News - February 16th, 2024 [February 16th, 2024]
- Uruguay becomes latest nation to join NASA's Artemis Accords - UPI News - February 16th, 2024 [February 16th, 2024]
- An astronomer's lament: Satellite megaconstellations are ruining space exploration - The Conversation - February 16th, 2024 [February 16th, 2024]
- Asteroid Mining: A Glimpse into the Future - Medriva - February 16th, 2024 [February 16th, 2024]
- Singapore's ESS and Australia's ELA Join Forces to Redefine Space Exploration - BNN Breaking - February 16th, 2024 [February 16th, 2024]
- Intuitive Machines makes history with lunar lander launch - InnovationMap - February 16th, 2024 [February 16th, 2024]
- The Potential of Minimoons in Interplanetary Exploration and Space Travel - Medriva - February 16th, 2024 [February 16th, 2024]
- In space exploration, Switzerland punches above its weight - SWI swissinfo.ch - SWI swissinfo.ch in English - February 16th, 2024 [February 16th, 2024]
- Odysseus Mission: Pioneering the Lunar Economy and Space Exploration - BNN Breaking - February 16th, 2024 [February 16th, 2024]
- Starlab Announces Leadership Team With new CEO and CFO - SpaceWatch.Global - February 16th, 2024 [February 16th, 2024]
- The New Space Race: Private American Companies Compete to Land on the Moon - Medriva - February 16th, 2024 [February 16th, 2024]
- Spectrum Advanced Manufacturing Technologies Plays Vital Role in NASA's Deep Space Optical Communications - PR Newswire - February 16th, 2024 [February 16th, 2024]
- Intuitive Machines Odyssey lunar lander to be launched early Wednesday - The Washington Post - February 16th, 2024 [February 16th, 2024]
- New funding for space projects ensures the UK's role in global missions - Innovation News Network - February 16th, 2024 [February 16th, 2024]
- SpaceX and Intuitive Machines Lunar Mission: Challenges, Expectations, and Future - Medriva - February 16th, 2024 [February 16th, 2024]
- Farewell to a NASA Hero: Apollo Astronaut Thomas K. Mattingly II Departs at 87 - SciTechDaily - November 4th, 2023 [November 4th, 2023]
- NASA Welcomes Netherlands as Newest Artemis Accords Signatory - NASA - November 4th, 2023 [November 4th, 2023]
- China's astronauts tend orbital garden to aid deep space exploration - Space.com - November 4th, 2023 [November 4th, 2023]
- All-UK astronaut mission shows that private enterprise is vital to the ... - The Conversation Indonesia - November 4th, 2023 [November 4th, 2023]
- Former Astronaut Discusses Space Travel and Its Future With ... - Duke Today - November 4th, 2023 [November 4th, 2023]
- Returning astronauts to the moon is NASA's biggest challenge, but ... - Space.com - November 4th, 2023 [November 4th, 2023]
- Australias IPSEC Conference Shows Synergies Between the Space ... - Via Satellite - November 4th, 2023 [November 4th, 2023]
- Mice embryos successfully grown in space, a promising milestone ... - Salon - November 4th, 2023 [November 4th, 2023]
- Dava Newman talks Mars exploration and comunication - CMU The Tartan Online - November 4th, 2023 [November 4th, 2023]
- Science Fact or Fiction: Leveraging Space to Transform Medicine - Kennedy Space Center - November 4th, 2023 [November 4th, 2023]
- Now astronauts will not get lost in space - SAMAA - November 4th, 2023 [November 4th, 2023]
- Sci-fi inspired tractor beams are real, and could solve a major space ... - Livescience.com - November 4th, 2023 [November 4th, 2023]
- Mining Meets Space: Revolutionizing Industry Innovation with Cross ... - AZoMining - November 4th, 2023 [November 4th, 2023]
- Surf's up: Catch an atmospheric wave as ASU research team ... - ASU News Now - November 4th, 2023 [November 4th, 2023]
- Ron Baron says Tesla's valuation can hit $4 trillion, but 'SpaceX has ... - Morningstar - November 4th, 2023 [November 4th, 2023]