[ChallyTatum]

Let me break it down again.

You admit the graph describes motion that is continuous then you somehow twist that around to say that it does not mean the velocity is never zero.

A smooth continuous displacement curve does not mean velocity is never zero. Again take the derivative of the piston's displacement curve and note the points at which it's velocity is zero.

The piston does change direction but it does not become motionless. As soon as the EE I was talking to suggested the best way to look at the problem was imagining a motion of the rotation of the crankshaft and rod bearing journal describing a sine wave then it became clear to me that the piston does not stop.

I have told you how to mathematically (calculus) and graphically prove the piston's velocity at TDC and BDC of a running engine is zero. These methods are used in classical mechanics and in FEA software that helps simulate and analyze ICE design/operations. BTW the displacement sine curve you keep referring to that describes the pistons displacement over time is derived from classical mechanics.

It is a hard concept to accept. I was convinced it does have to stop -- I dare say it "looks" like it has to stop -- but it doesn't/can't stop.

Why? If you can't explain it either you don't understand the concept, the concept is flawed or requires a different discipline to describe.

Years prior I had a rather lengthy discussion with my geometry instructor on the subject of a baseball being thrown straight up in a geometrically straight line. Absent any outside forces other than gravity the ball continues up until it begins to come down again. Of course I believed it had to stop. But the instructor convinced me it did not. I did not copy down what was on the chalkboard.

Lol, sounds like your geometry instructor was speaking outside of classical mechanics an into the realm of quantum mechanics which how the hell did he sketch that on the chalkboard? Sounds like he was discussing the uncertainty principle in which we cannot know both the position and speed of a particle, such as a photon or electron, with perfect accuracy. In that case, nothing is ever at rest except at 0 kelvin in which all particle motion stops and disorder disappears. Simply put you then cannot use your sine wave displacement curve example (derived from classical and not quantum mechanics) to describe the location of the piston, if anything the curve would not be a line but a cloud of infinite points.

BTW here is an answer to your ball in the air example.

So if you are talking classical mechanics, which you keep bringing up the displacement curve derived from classical mechanics, you are wrong.

 

[Too Fast]

W stands for Winter. As in, 5W30 I was always taught it means it flows like a 5W oil at 0 or some cold temp, and 30 at normal operating temps. I could google it, but that's too easy.

 

[ChallyTatum]

W stands for Winter. As in, 5W30 I was always taught it means it flows like a 5W oil at 0 or some cold temp, and 30 at normal operating temps. I could google it, but that's too easy.

But what if I live at the equator, there is no winter? Years ago my geography teacher convinced me that at the equator there is no winter so people at the equator should not buy any oil that has a W in it.

 

[A Guy]

I live in California...so I just need "20"?

As to the continuous "the Earth is flat" discussion, I'm done with that...

A Guy

 

[Too Fast]

But what if I live at the equator, there is no winter? Years ago my geography teacher convinced me that at the equator there is no winter so people at the equator should not buy any oil that has a W in it.

...uuummmmmm....lol

OMG...I finally watched the video, re-affirming what I already knew, but you can always learn something. He said the piston stops at TDC and BDC. OK, OK, I will not say anything further about that.

 

[CE9311]

 

[jmac65]

Where is Sheldon Cooper when we need him?

 

[ChallyTatum]

Sounds like someone might still be in the matrix.

OMG...I finally watched the video, re-affirming what I already knew, but you can always learn something. He said the piston stops at TDC and BDC. OK, OK, I will not say anything further about that.

I think that is what prompted Rockster's nugget of wisdom. I love how he only picks out words and phrases that fits his narrative.

 

[Rockster]

I think that is what prompted Rockster's nugget of wisdom. I love how he only picks out words and phrases that fits his narrative.

You chose to ignore the very visual graphical representation the piston does not stop because it follows the sine wave described by the rotation of the crankshaft and the rod journal. As I believe I mentioned early on when I believed the piston stopped I was told the simplest way of visualizing this was not the case was the graphical representation I mentioned above. Rather than requiring hours of hand waving I almost instantly realized what was going on.

I know it does seem hard to believe the piston doesn't stop but the curve of the sine wave has no section that would allow for this. Anything that receives its motion from something that describes this curve does not stop even though it changes direction.

If you can't see this I can't think of any way to make it plainer.

And we'll just have to agree to disagree. Fortunately pistons will still move in their cylinders, valves will continue to up then down, and engines will still work regardless of our disagreement on this.

 

[A Guy]

A Guy

 

[ChallyTatum]

You chose to ignore the very visual graphical representation the piston does not stop because it follows the sine wave described by the rotation of the crankshaft and the rod journal. As I believe I mentioned early on when I believed the piston stopped I was told the simplest way of visualizing this was not the case was the graphical representation I mentioned above. Rather than requiring hours of hand waving I almost instantly realized what was going on.

I know it does seem hard to believe the piston doesn't stop but the curve of the sine wave has no section that would allow for this. Anything that receives its motion from something that describes this curve does not stop even though it changes direction.

If you can't see this I can't think of any way to make it plainer.

And we'll just have to agree to disagree. Fortunately pistons will still move in their cylinders, valves will continue to up then down, and engines will still work regardless of our disagreement on this.

Looks like you forgot to read this post where I breakdown your false belief.

Oil Viscosity Explained

Let me break it down again. You admit the graph describes motion that is continuous then you somehow twist that around to say that it does not mean the velocity is never zero. A smooth continuous displacement curve does not mean velocity is never zero. Again take the derivative of the...

www.challengertalk.com

I will also say you really have no business helping folks on this forum if you still believe a piston in a running engine never hits zero velocity. I also proved it visually with graphs but your blind faith in your geometry teacher's rhetoric , which you can't even prove or explain, has you so twisted you literally are talking out your arse.

 

[Rys Black Beauty]

Wow, you guys still arguing about this trying to prove a point that is not even a take away from the original video! Hopefully you at least got the point to use the oil viscosity recommended for your engine! Especially with the Challenger, and any of the engines running Variable Valve Timing, as that recommended oil viscosity is very important in that feature running properly.

 

[ChallyTatum]

Wow, you guys still arguing about this trying to prove a point that is not even a take away from the original video! Hopefully you at least got the point to use the oil viscosity recommended for your engine! Especially with the Challenger, and any of the engines running Variable Valve Timing, as that recommended oil viscosity is very important in that feature running properly.

If you read my earlier posts I did. Also I don't argue but simply explain why I am right. But in all seriousness, thinking the piston never achieves zero velocity is up there with thinking the earth is flat.

BTW here is yet another link deriving and explaining kinematic analysis of the ICE piston.

https://x-engineer.org/kinematic-analysis-piston/#:~:text=When%20the%20piston%20is%20going,function%20of%20the%20crank%20angle

.

 

[Tape]

ChallyTatum, instead of Rockster try talking to this:

I believe you would do just as well.

 

[CE9311]

ChallyTatum, instead of Rockster try talking to this:

I believe you would do just as well.

Why post this? Why drag this back up? That same wall would be of same use for them as it would you when you get down to the brass tacks of it all.

Jesus let it goes folks. Be happy the oil salesman doesn't come here like he use to over on the CF pages.