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A valve spring inside a running engine does more than compress and release. The spring also rotates slowly along its axis with each cycle, and that rotation is intentional. The valve face strikes the same metal seat thousands of times a minute, and without rotation any single contact point... show more

Mechanical Knowledge

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37,986 views • 5 days ago •via X (Twitter)

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Hip rotation is one of the primary drivers of velocity during the throw. Both speed and timing of rotation matter. The goal is to have the hips rotate out in front of the torso. Ideally, you want rotation to begin quickly after the front foot strikes the ground. The speed of rotation is also critical. I strive for all QBs that I work with to be 800+ deg/sec with hip rotation speed. One key thing is to not mistake “sliding” for rotating. Many will push and slide their hips forward as opposed to rotating against a stable lead leg.

Hip rotation is one of the primary drivers of velocity during the throw. Both speed and timing of rotation matter. The goal is to have the hips rotate out in front of the torso. Ideally, you want rotation to begin quickly after the front foot strikes the ground. The speed of rotation is also critical. I strive for all QBs that I work with to be 800+ deg/sec with hip rotation speed. One key thing is to not mistake “sliding” for rotating. Many will push and slide their hips forward as opposed to rotating against a stable lead leg.

Joe Mohr

12,621 views • 2 months ago

It's always fascinating to watch the outflow valve (OFV) close during takeoff. This marks the beginning of the aircraft’s pre-pressurisation cycle. While it does provide a smoother transition to pressurised flight and improves passenger comfort, its main purpose goes beyond that. The primary reason for closing the outflow valve at takeoff is to prevent a slight pressure bump that occurs during aircraft rotation. At high angles of attack, an air cushion effect forms over the aft outflow valve, which can cause a momentary reverse airflow - potentially pushing air back into the cabin through the OFV. This pre-pressurization prevents FOD from being blown into the cabin, and this is also the reason the airplane lands with a slightly pressurized cabin. #FunFact

It's always fascinating to watch the outflow valve (OFV) close during takeoff. This marks the beginning of the aircraft’s pre-pressurisation cycle. While it does provide a smoother transition to pressurised flight and improves passenger comfort, its main purpose goes beyond that. The primary reason for closing the outflow valve at takeoff is to prevent a slight pressure bump that occurs during aircraft rotation. At high angles of attack, an air cushion effect forms over the aft outflow valve, which can cause a momentary reverse airflow - potentially pushing air back into the cabin through the OFV. This pre-pressurization prevents FOD from being blown into the cabin, and this is also the reason the airplane lands with a slightly pressurized cabin. #FunFact

Arjun Singh

23,735 views • 3 months ago

𝐗𝐀𝐑𝐘𝐔 𝐆𝐈𝐕𝐄𝐒 𝐓𝐀𝐊𝐄 𝐎𝐍 𝐔𝐏𝐂𝐎𝐌𝐈𝐍𝐆 𝐑𝐎𝐓𝐀𝐓𝐈𝐎𝐍 𝐇𝐄𝐋𝐏𝐄𝐑 𝐈𝐍 𝐖𝐎𝐖 In an attempt to make the game more approachable for new players and less reliant on 3rd party add-ons, the World of Warcraft team has announced that a rotation helper will be added to retail WoW. The rotation helper will have an additional option for a 1 button rotation option which has obviously sparked a conversation within the community. WoW streamer, Josh Lujan, has given his take on the situation saying that the rotation helper feels like a violation to WoW gameplay.

𝐗𝐀𝐑𝐘𝐔 𝐆𝐈𝐕𝐄𝐒 𝐓𝐀𝐊𝐄 𝐎𝐍 𝐔𝐏𝐂𝐎𝐌𝐈𝐍𝐆 𝐑𝐎𝐓𝐀𝐓𝐈𝐎𝐍 𝐇𝐄𝐋𝐏𝐄𝐑 𝐈𝐍 𝐖𝐎𝐖 In an attempt to make the game more approachable for new players and less reliant on 3rd party add-ons, the World of Warcraft team has announced that a rotation helper will be added to retail WoW. The rotation helper will have an additional option for a 1 button rotation option which has obviously sparked a conversation within the community. WoW streamer, Josh Lujan, has given his take on the situation saying that the rotation helper feels like a violation to WoW gameplay.

N_Tys

280,815 views • 1 year ago

The 3D learning experience is thinking an idea I came up with is cool and spent hours implementing it to find out that it only works for a very specific situation aka it’s useless. HAHA Basically I rigged the collar with their own bones so they don’t deform weirdly with the arm/shoulder movement then realise the sleeve clips into the collar on Z rotation. Decided to try applying the twist bone logic of bone constraints (copy rotation) and was like wow, it kinda works to move the collar away when the arm rotates to the front! But reality is that it just looks nice on T-pose and the “effect” is weird when the arms are posed downwards (which would be the default state of the model in its intended use)… And also the sleeve will still clip into the collar at a more extreme rotation anyway so I guess it was a fruitless effort in the end hahaha It did help me get more comfortable with the idea of applying bone constraints for other uses tho so that’s a plus! ദ്ദി(•⥿•)ว✨ In the end I’ll probably have colliders on the sleeve to prevent clipping with the collar as much as possible but I think a big degree of clipping is still inevitable considering the range of movement when the model is used for 3D vtubing 🤔

The 3D learning experience is thinking an idea I came up with is cool and spent hours implementing it to find out that it only works for a very specific situation aka it’s useless. HAHA Basically I rigged the collar with their own bones so they don’t deform weirdly with the arm/shoulder movement then realise the sleeve clips into the collar on Z rotation. Decided to try applying the twist bone logic of bone constraints (copy rotation) and was like wow, it kinda works to move the collar away when the arm rotates to the front! But reality is that it just looks nice on T-pose and the “effect” is weird when the arms are posed downwards (which would be the default state of the model in its intended use)… And also the sleeve will still clip into the collar at a more extreme rotation anyway so I guess it was a fruitless effort in the end hahaha It did help me get more comfortable with the idea of applying bone constraints for other uses tho so that’s a plus! ദ്ദി(•⥿•)ว✨ In the end I’ll probably have colliders on the sleeve to prevent clipping with the collar as much as possible but I think a big degree of clipping is still inevitable considering the range of movement when the model is used for 3D vtubing 🤔

𝗞𝗔𝗥𝗜𝗛𝗔 🌘🍀 3D Artist ☻

128,210 views • 6 months ago

Here's a 70 minute video of my thoughts on why this could be a set-up for a rotation to broaden the bull market to various sectors and markets rather than the beginning of an impending crash. Have a great weekend, everyone! 🐱 Timestamps below: 00:00 1) Large to small cap rotation. $QQQ $IWM 09:30 2) S&P500 to NASDAQ rotation. $SPY $QQQ 13:00 3) Tech sector rotation. $IGV $NVDA $MSFT $GOOGL $AMZN $TSLA 24:00 4) Rotation into dividend stocks to broaden rally: $SCHD 29:00 5) Rotation into other sectors to broaden rally: $XLI $XLU 31:30 6) Rotation and cool down of risk-on: $ARKK 37:00 7) Rotation from $Gold and $Silver? 43:50 8) China and Japan $HSI $NIKKEI 53:10 9) #Bitcoin bottoming out? 1:00:40 10) Rotation to #Ethereum and #Altcoins?

Here's a 70 minute video of my thoughts on why this could be a set-up for a rotation to broaden the bull market to various sectors and markets rather than the beginning of an impending crash. Have a great weekend, everyone! 🐱 Timestamps below: 00:00 1) Large to small cap rotation. $QQQ $IWM 09:30 2) S&P500 to NASDAQ rotation. $SPY $QQQ 13:00 3) Tech sector rotation. $IGV $NVDA $MSFT $GOOGL $AMZN $TSLA 24:00 4) Rotation into dividend stocks to broaden rally: $SCHD 29:00 5) Rotation into other sectors to broaden rally: $XLI $XLU 31:30 6) Rotation and cool down of risk-on: $ARKK 37:00 7) Rotation from $Gold and $Silver? 43:50 8) China and Japan $HSI $NIKKEI 53:10 9) #Bitcoin bottoming out? 1:00:40 10) Rotation to #Ethereum and #Altcoins?

Cantonese Cat 🐱🐈

62,621 views • 4 months ago

Stop instantly rotating back. I see so many players panic and rush back to defense, only to take the worst possible rotation path. While rotations and recovery are important in solo queue, you should always take the correct rotation path before committing to it. A simple guideline is to avoid rotating to the same side your teammate’s nose is pointing. This will give you better field coverage and naturally put you into the correct rotation. Here is a player who repeatedly rotates to the same side as his teammate and gets scored on because of it.

Stop instantly rotating back. I see so many players panic and rush back to defense, only to take the worst possible rotation path. While rotations and recovery are important in solo queue, you should always take the correct rotation path before committing to it. A simple guideline is to avoid rotating to the same side your teammate’s nose is pointing. This will give you better field coverage and naturally put you into the correct rotation. Here is a player who repeatedly rotates to the same side as his teammate and gets scored on because of it.

KINSEH

29,567 views • 6 months ago

I came, I saw, I KICKED IT'S ASS! Check out my new oam engine running in my updated Mega Man II port to the Super Nintendo! I've also included a 2nd video of the OG game in action. I'm using Metal Man's stage as a perfect example. I'm also showing the sprite viewer of Mesen, to show there is no OAM rotation every other frame, and I'm also showing my OAM buffer which is 200 bytes in size. I've removed the OAM rotation the game does, and prioritized the health/weapon bars to be drawn first. I am VERY proud of the changes i've made to the OAM engine. 🙂

I came, I saw, I KICKED IT'S ASS! Check out my new oam engine running in my updated Mega Man II port to the Super Nintendo! I've also included a 2nd video of the OG game in action. I'm using Metal Man's stage as a perfect example. I'm also showing the sprite viewer of Mesen, to show there is no OAM rotation every other frame, and I'm also showing my OAM buffer which is 200 bytes in size. I've removed the OAM rotation the game does, and prioritized the health/weapon bars to be drawn first. I am VERY proud of the changes i've made to the OAM engine. 🙂

infidelity

10,390 views • 3 months ago

Arteta on Martin Zubimendi’s lack of rotation: “Well, there's been more rotation than I think any other team. So in some areas there are less. I think that's the one particular one that you are mentioning, probably.” On Zubimendi struggling for form: “Well, because obviously when you play that many games, to maintain the excellent level is almost impossible. “I haven't seen a single player probably in the Premier League this season to be able to do that. So, again, it's part of that journey as a player and the shorter it is, the better.” Reporter: “Do you get the sense that he's got the kind of mentality required to get through this particular moment?” “Yeah, because he's been so consistent and so intelligent and because he demands himself more than anybody else probably.”

Arteta on Martin Zubimendi’s lack of rotation: “Well, there's been more rotation than I think any other team. So in some areas there are less. I think that's the one particular one that you are mentioning, probably.” On Zubimendi struggling for form: “Well, because obviously when you play that many games, to maintain the excellent level is almost impossible. “I haven't seen a single player probably in the Premier League this season to be able to do that. So, again, it's part of that journey as a player and the shorter it is, the better.” Reporter: “Do you get the sense that he's got the kind of mentality required to get through this particular moment?” “Yeah, because he's been so consistent and so intelligent and because he demands himself more than anybody else probably.”

Connor Humm

401,479 views • 3 months ago

🚨 JUST IN: Vice President JD Vance is stepping up at the White House today and filling in for Karoline Leavitt as press secretary at 11AM, and honestly this is the kind of rotation that makes politics fun again. JD absolutely crushed it last time because he does not walk into that room scared of the media, he walks in ready for the fight, ready with facts, ready with confidence, and ready to remind every reporter in that room that the Trump White House is not there to be bullied by the same press corps that spent years lying to Americans. Karoline has been a machine at the podium, but JD behind that microphone is a different kind of entertainment because he can take their fake outrage, flip it back on them, and make the entire room look ridiculous without even raising his voice. Now the only question is simple: Is Marco next in the rotation after JD? 🤣🇺🇸

🚨 JUST IN: Vice President JD Vance is stepping up at the White House today and filling in for Karoline Leavitt as press secretary at 11AM, and honestly this is the kind of rotation that makes politics fun again. JD absolutely crushed it last time because he does not walk into that room scared of the media, he walks in ready for the fight, ready with facts, ready with confidence, and ready to remind every reporter in that room that the Trump White House is not there to be bullied by the same press corps that spent years lying to Americans. Karoline has been a machine at the podium, but JD behind that microphone is a different kind of entertainment because he can take their fake outrage, flip it back on them, and make the entire room look ridiculous without even raising his voice. Now the only question is simple: Is Marco next in the rotation after JD? 🤣🇺🇸

ⁿᵉʷˢ Barron Trump 🇺🇸

181,385 views • 26 days ago

Ok, this is crazy... The US Air Force found out in 1971 that the rotation of the Earth is driven by the Earth's magnetic field. They knew that it would eventually slow down with the magnetic decoupling and the shifting of the poles. Douglas Vogt tried to warn us in 2018, and of course, he was labeled as 'crazy'. But studies in 2023 and 2024 have started appearing about the Earth's core rotation slowing down almost to a full stop. Also, NASA recently admitted that the rotation of the Earth changes due to the melting of glaciers and human-driven climate change. Of course, this is because of the geomagnetic excursion. Make no mistake, they will play this game until the very end. They will give you 'alternative explanations' and blame you for the chaos that is coming. They will give you false hope while they prepare their doomsday bunkers. This happens every 12,000 years (with smaller events every 6000 years), and I will share more proof in the comments section. You will see that Elon Musk knows, Donald Trump is aware of these changes, and the plan of the 'elite' leaked in 2010. I will continue sharing more information about this cycle while they want you to stay ignorant of this reality.

Ok, this is crazy... The US Air Force found out in 1971 that the rotation of the Earth is driven by the Earth's magnetic field. They knew that it would eventually slow down with the magnetic decoupling and the shifting of the poles. Douglas Vogt tried to warn us in 2018, and of course, he was labeled as 'crazy'. But studies in 2023 and 2024 have started appearing about the Earth's core rotation slowing down almost to a full stop. Also, NASA recently admitted that the rotation of the Earth changes due to the melting of glaciers and human-driven climate change. Of course, this is because of the geomagnetic excursion. Make no mistake, they will play this game until the very end. They will give you 'alternative explanations' and blame you for the chaos that is coming. They will give you false hope while they prepare their doomsday bunkers. This happens every 12,000 years (with smaller events every 6000 years), and I will share more proof in the comments section. You will see that Elon Musk knows, Donald Trump is aware of these changes, and the plan of the 'elite' leaked in 2010. I will continue sharing more information about this cycle while they want you to stay ignorant of this reality.

Open Minded Approach

1,536,405 views • 1 year ago

Asked Chris Finch about the adjustment in Mike Conley's role this season and what that process has been like. In his answer he talked a bit about the rotation big picture "We're getting up to the point here where we might even shrink the rotation a little bit smaller, and then everybody (who plays) minutes will level out". For context, the Wolves have been playing a 10-man rotation for most of the season, but with the 9th and 10th guys often playing between 4 and 8 total minutes. So I read that as the leveling out coming in the form of removing one guy so everyone who plays is receiving 10+ minutes a night. These were the 10 players who played tonight while the Wolves were at full-strength Gobert Randle McDaniels (got hurt tonight) Edwards DiVincenzo Reid Conley Hyland Shannon Clark (Rob Dillingham has not been in the 10-man rotation of late when the Wolves are at full-strength.)

Asked Chris Finch about the adjustment in Mike Conley's role this season and what that process has been like. In his answer he talked a bit about the rotation big picture "We're getting up to the point here where we might even shrink the rotation a little bit smaller, and then everybody (who plays) minutes will level out". For context, the Wolves have been playing a 10-man rotation for most of the season, but with the 9th and 10th guys often playing between 4 and 8 total minutes. So I read that as the leveling out coming in the form of removing one guy so everyone who plays is receiving 10+ minutes a night. These were the 10 players who played tonight while the Wolves were at full-strength Gobert Randle McDaniels (got hurt tonight) Edwards DiVincenzo Reid Conley Hyland Shannon Clark (Rob Dillingham has not been in the 10-man rotation of late when the Wolves are at full-strength.)

Dane Moore

14,193 views • 6 months ago

It's easier to explain why the moon shouldn't exist than why it does. All theories of lunar origin don't make sense. The moon's mass and assumed density suggest it should have settled into spherical form... with a single center of mass. Free to rotate on any axis. But the moon's rotation is completely and precisely locked to its orbital period around Earth. This implies mass is not distributed radially symmetrical. A huge anomaly. Something within the lunar crust is extremely rigid.

It's easier to explain why the moon shouldn't exist than why it does. All theories of lunar origin don't make sense. The moon's mass and assumed density suggest it should have settled into spherical form... with a single center of mass. Free to rotate on any axis. But the moon's rotation is completely and precisely locked to its orbital period around Earth. This implies mass is not distributed radially symmetrical. A huge anomaly. Something within the lunar crust is extremely rigid.

Randall Carlson

29,758 views • 6 months ago

This paper is describing something which sounds remarkably similar to an ECDO state 2 to state 1 rotation a half a billion years ago. Excerpts from Evidence for a Large-Scale Reorganization of Early Cambrian Continental Masses by Inertial Interchange True Polar Wander, Kirschvink et al. (1997): "..at least two tectonic plates, involving more than two-thirds of Earth's continental lithosphere, were involved in a rapid rotation of ~90° relative to the spin axis. We speculate that the entire lithosphere may have been involved in this rotation. // The new ages, along with paleomagnetic data, indicate that continents moved at rapid rates that are difficult to reconcile with our present understanding of mantle dynamics. // The pole for this sequence is >80° away from the Vendian-Early Cambrian poles, implying that Australia underwent a large rotation while remaining near the equator sometime between Tommotian and Late Cambrian time. // Australia rotated counterclockwise during this time. // Antarctica, India, Africa, South America, and perhaps parts of East Asia also rotated with Australia. // True polar wander (TPW) is the process through which quasi-rigid spheroids align their maximum moments of inertia with the spin axis, pushing positive mass anomalies toward the rotational equator. // A variant of this mechanism, inertial interchange true polar wander (IITPW), involves discrete bursts of TPW of up to 90° in geologically short intervals of time if the magnitudes of the intermediate and maximum moments of inertia cross. This would result in a rapid movement away from the spin axis by the geographic location of the former pole with rotation of the entire solid Earth centered about the minimum moment of inertia located on the equator. // These two poles, with their stated polarity interpretation, are separated by about 68°; together they yield a plausible tropical position for Siberia, nearly on the opposite side of the globe from Australia. // If the velocities are due to TPW, however, such geodynamical considerations are obviated because the entire mantle would have rotated along with the lithosphere." [1] [2] (by Ethical Skeptic ☀)

This paper is describing something which sounds remarkably similar to an ECDO state 2 to state 1 rotation a half a billion years ago. Excerpts from Evidence for a Large-Scale Reorganization of Early Cambrian Continental Masses by Inertial Interchange True Polar Wander, Kirschvink et al. (1997): "..at least two tectonic plates, involving more than two-thirds of Earth's continental lithosphere, were involved in a rapid rotation of ~90° relative to the spin axis. We speculate that the entire lithosphere may have been involved in this rotation. // The new ages, along with paleomagnetic data, indicate that continents moved at rapid rates that are difficult to reconcile with our present understanding of mantle dynamics. // The pole for this sequence is >80° away from the Vendian-Early Cambrian poles, implying that Australia underwent a large rotation while remaining near the equator sometime between Tommotian and Late Cambrian time. // Australia rotated counterclockwise during this time. // Antarctica, India, Africa, South America, and perhaps parts of East Asia also rotated with Australia. // True polar wander (TPW) is the process through which quasi-rigid spheroids align their maximum moments of inertia with the spin axis, pushing positive mass anomalies toward the rotational equator. // A variant of this mechanism, inertial interchange true polar wander (IITPW), involves discrete bursts of TPW of up to 90° in geologically short intervals of time if the magnitudes of the intermediate and maximum moments of inertia cross. This would result in a rapid movement away from the spin axis by the geographic location of the former pole with rotation of the entire solid Earth centered about the minimum moment of inertia located on the equator. // These two poles, with their stated polarity interpretation, are separated by about 68°; together they yield a plausible tropical position for Siberia, nearly on the opposite side of the globe from Australia. // If the velocities are due to TPW, however, such geodynamical considerations are obviated because the entire mantle would have rotated along with the lithosphere." [1] [2] (by Ethical Skeptic ☀)

Craig Stone

16,334 views • 1 year ago

James Harden on the 3-7 Clippers: “We haven’t had any consistency, for real… We’ve had so many different lineups, so many guys in and out of the rotation… Guys are all over the place. Some guys haven’t played in ever. Some guys are just put in the rotation. Some guys are new here. It’s a lot that goes into it.”

James Harden on the 3-7 Clippers: “We haven’t had any consistency, for real… We’ve had so many different lineups, so many guys in and out of the rotation… Guys are all over the place. Some guys haven’t played in ever. Some guys are just put in the rotation. Some guys are new here. It’s a lot that goes into it.”

Joey Linn

236,064 views • 8 months ago

The tighter the fit, the faster the failure. What you’re looking at is a mechanical paradox that took engineers over a century to master. In the world of heavy machinery, "perfectly tight" is a death sentence. Even the most advanced machines on Earth are designed with a deliberate, microscopic gap between every gear tooth. If you make them perfectly flush, they don’t just wear down: they seize, weld, and explode in a matter of seconds. As these gears rotate, the laws of thermodynamics are unforgiving. Friction generates intense heat, causing the metal to expand. Without that sliver of space, the gears have nowhere to grow, turning a million-dollar precision machine into a solid block of scrap in an instant. That tiny gap is where oil breathes and heat escapes. It is the only thing standing between smooth, silent rotation and catastrophic destruction. True precision isn't about zero clearance; it’s about mastering the room for reality.

The tighter the fit, the faster the failure. What you’re looking at is a mechanical paradox that took engineers over a century to master. In the world of heavy machinery, "perfectly tight" is a death sentence. Even the most advanced machines on Earth are designed with a deliberate, microscopic gap between every gear tooth. If you make them perfectly flush, they don’t just wear down: they seize, weld, and explode in a matter of seconds. As these gears rotate, the laws of thermodynamics are unforgiving. Friction generates intense heat, causing the metal to expand. Without that sliver of space, the gears have nowhere to grow, turning a million-dollar precision machine into a solid block of scrap in an instant. That tiny gap is where oil breathes and heat escapes. It is the only thing standing between smooth, silent rotation and catastrophic destruction. True precision isn't about zero clearance; it’s about mastering the room for reality.

Mathematica

83,519 views • 4 months ago

Why is the CRJ tricky to land? The CRJ’s main landing gear sits behind the center of rotation, making the flare less forgiving—pitch a bit too much and you risk driving the gear onto the runway. On top of that, the struts are quite sensitive and can compress quickly, so if not carefully managed, it can result in a firm landing. 📹: YVRplanes

Why is the CRJ tricky to land? The CRJ’s main landing gear sits behind the center of rotation, making the flare less forgiving—pitch a bit too much and you risk driving the gear onto the runway. On top of that, the struts are quite sensitive and can compress quickly, so if not carefully managed, it can result in a firm landing. 📹: YVRplanes

Turbine Traveller

125,139 views • 2 months ago