A discussion on TFES forum

[teo123]

Thinking v defines the speed relative to some arbitrary observer would be nonsensical.

Well, that's how I understood it in school and I got A. OK, I believe you.

you just need to understand the concept of equal and opposite forces for now.

Well, a force is, and you know it, a product of mass and acceleration. Why do you assume that the reaction mass will be accelerating? Doesn't the Torricelli's law say it should move at a constant speed? I don't know, I might have misunderstood it as well.

You need to learn to be sensible and trust experts.

If you realize you don't understand physics at all, it's very hard for you to believe there are people who can understand rocket science, right?

The force is inward, and so is your acceleration (because you're changing direction), so if you're sitting in Dumbo...
Image
...you feel pushed out (just as in the case of sitting in a car, and feeling pushed in the opposite direction of the car's acceleration, back against the seat behind you when you're speeding up, because the seat is pushing on you).
This is probably your false assumption.
On Earth, due to gravity your body is trying to accelerate down, but the ground is pushing back up at you with the normal force (like the car's seat pushing on you when you're "stationary" in the car, just the reference frame is shifted to an 'accelerated' [in a conventional sense] body being "stopped" rather than a "stopped" body being 'accelerated'), so that's what you feel.

Makes sense. Just to see if I correctly understood you, the red ball in my diagram changes its momentum as the green ball circles around it because of the centrifugal force, right?

Do the math. How tall are those buildings? The one in the middle looks like 500 or so feet. How many blocks do they represent?
How tall are those clouds? Low-balling it, they may be 4,000 feet. Could easily be a lot higher. How broad an image is that ocean photo?
Photographic framing can be very deceptive, just based on zoom, irrespective of lenses.
Also, what angle are they being seen at? Because of the scale, the clouds are far above, being seen from below from a fairly wide angle lens. The buildings are being photographed from a distance along a level horizontal ray using an optical zoom (or the image has been cropped).
Also, you're doing the same thing with the lines again: in this case, making the lines seem to be parallel when they aren't. There is obviously some slight perspective in those edge buildings that the thick lines are covering up.

And if it were lenses again, it would make the sunrays appear curved, right?

They probably are curved. If not, the image may have been corrected on the computer. Kind of irrelevant, though, given the differences in scale of those images.

I don't understand what you are talking about. I assumed they are going to be parallel because of this:

The distance between the projections of the line p1 and the line p2 is going to be d, regardless of how much they extend in the direction parallel with the y-axis (vertical), right?

And I am not really sure if I understand the conservation of mechanical energy right.

If I correctly understand the law of lever, the right ball, after the left one hits the lever, should bounce to an altitude lower than h. If I correctly understand the law of the conservation of mechanical energy, then the right ball, after the left one hits the lever, should bounce to an altitude equal to h (gravitational potential energy).

[brimstoneSalad]

Well, a force is, and you know it, a product of mass and acceleration. Why do you assume that the reaction mass will be accelerating? Doesn't the Torricelli's law say it should move at a constant speed? I don't know, I might have misunderstood it as well.

After the reaction mass has exited the thruster, it will be moving at a constant velocity.

What do you call it when mass changes velocity? E.g. from the velocity of the rocket (the reaction mass inside the fuel tanks just sitting there) to the velocity of the emitted reaction mass speeding away from the rocket?

Answer: Acceleration.

Going from zero velocity relative to the rocket, to any other velocity, is acceleration, and that means a force is applied.

Do the math assuming that the reaction mass accelerates to its exiting velocity over 1 second (it's not instant, that's impossible and would require an infinite force), then you can figure out the force applied to the rocket body for that time.

If you realize you don't understand physics at all, it's very hard for you to believe there are people who can understand rocket science, right?

Humility and intellectual honesty can be hard.
It's much easier to just believe in religion, which even a child can feel like he or she understands.

Remember Socrates, "The only true wisdom is in knowing you know nothing."
It's an exaggeration, but it gets the point across (particularly in an era before science).

Makes sense. Just to see if I correctly understood you, the red ball in my diagram changes its momentum as the green ball circles around it because of the centrifugal force, right?

If it's not secured in place, it will be pulled slightly by the green ball, yes.
Is this a rod, or a string, or gravity?
The only direction it would be pulled is toward the green ball.

And if it were lenses again, it would make the sunrays appear curved, right?

Unless it were corrected for on the computer, yes. The clouds are extremely far away from the ground where the photo is being taken from (unlike the tops of the buildings, which are closer to an equal distance from wherever the photo is being taken in that image).

If you took a picture of the sun beams from an airplane, you could probably see them seeming to converge on the ground in the same way a building's base looks smaller from its top.

Perspective is complicated, and has to do with distance ratios.

We can see the same thing on smaller scales too:


You can make something look small or huge with perspective by changing the camera angle.
These sun beams appear to converge right behind the tree, maybe a few meters behind it -- is that where the sun is located?
No, it's located very far away.

You can figure all of this out with trigonometry.

I don't understand what you are talking about. I assumed they are going to be parallel because of this:

I really don't know what you're talking about.
We're mainly dealing with perspective here.

And I am not really sure if I understand the conservation of mechanical energy right.

You don't. The questions related to that diagram make a bunch of assumptions.
In the case of that setup in reality, a substantial amount of energy is going to be transferred into the apparatus, and if secured, into the Earth.
You need a simpler diagram.

If I correctly understand the law of lever, the right ball, after the left one hits the lever, should bounce to an altitude lower than h. If I correctly understand the law of the conservation of mechanical energy, then the right ball, after the left one hits the lever, should bounce to an altitude equal to h (gravitational potential energy).

The problem is that this set up does not transfer the energy between the balls. Levers deal with torque, which is angular.
It removes only some of the energy in the left falling ball, then the left ball retains enough energy to roll off to the left. Because of the angle of the lever, the right ball is propelled up AND left with the energy given to it. It will not go anywhere nearly as high, because a large part of the energy is retained in or retained by the original ball as it bounces, and also transferred into horizontal momentum of the right ball -- a substantial amount is also applied to the apparatus (as a right pushing force, to balance out the leftward forces applied to the balls from the apparatus).

You need to restrain the balls so no horizontal movement can occur. In such a case, and with no friction or air resistance, and perfect collisions that transfer all energy, then the right ball would go as high as the left one. This is never something that will occur in reality, though.

[teo123]

Humility and intellectual honesty can be hard.
It's much easier to just believe in religion, which even a child can feel like he or she understands.
Remember Socrates, "The only true wisdom is in knowing you know nothing."
It's an exaggeration, but it gets the point across (particularly in an era before science).

I've never heard of anyone claiming to understand the religion. They always say things like "Well, God has his mysterious reasons."
I am still not convinced that it is bad to believe in conspiracy theories. I mean, look, if you believe that humans were able to get to the Moon, that kind of implies that you can do anything if you make enough effort. It's a bit dangerous to think that, isn't it?
I realize that I crossed every single line. On forums, I used some arguments for which I knew exactly why they are false. In real life, I insulted a friend by claiming that he was a part of the conspiracy because he claimed that airplanes exist and that he was in one. He, of course, asked me how did I thing he had got there if airplanes didn't exist, and I told him that I didn't owe him that answer and that he could prove dragons exactly the same way (seriously!). He said we were not friends any more and left. It's hard for me to figure out what was I thinking when I said that. Was I serious? Was I trying to be funny? I mean, now I cry when I remember that conversation.
But you don't have to be like that to be a conspiracy theorists. What do you think?

Unless it were corrected for on the computer, yes. The clouds are extremely far away from the ground where the photo is being taken from (unlike the tops of the buildings, which are closer to an equal distance from wherever the photo is being taken in that image).
If you took a picture of the sun beams from an airplane, you could probably see them seeming to converge on the ground in the same way a building's base looks smaller from its top.
Perspective is complicated, and has to do with distance ratios.
We can see the same thing on smaller scales too:
You can make something look small or huge with perspective by changing the camera angle.
These sun beams appear to converge right behind the tree, maybe a few meters behind it -- is that where the sun is located?
No, it's located very far away.
You can figure all of this out with trigonometry.

I know that, I was referring to the case when one of the beams is obviously vertical (as on the photograph I've shown). Vertical lines don't appear to converge because of the perspective. How do you draw a cube? And there is a simple geometry behind that (vertical lines not appearing to converge because of the perspective).

You don't. The questions related to that diagram make a bunch of assumptions.
In the case of that setup in reality, a substantial amount of energy is going to be transferred into the apparatus, and if secured, into the Earth.
You need a simpler diagram.

Don't blame me. I asked my physics teacher that question and she said she didn't know.

You need to restrain the balls so no horizontal movement can occur. In such a case, and with no friction or air resistance, and perfect collisions that transfer all energy, then the right ball would go as high as the left one. This is never something that will occur in reality, though.

I don't understand. Unless those two balls, in the moment they both touch the lever, are equally distant from the triangle in the middle, the force acting on the right ball is going to be different from the force the left ball applied to the lever when colliding with it, so the right ball can't go to the same height as the left ball, right?

[brimstoneSalad]

I've never heard of anyone claiming to understand the religion. They always say things like "Well, God has his mysterious reasons."

They think they understand it -- the answer to everything is "god". They think of god like a person, so they understand the world in the same way we understand that another person has creative inclinations and has drawn a drawing. Why is there a tree by the house? Because the artist wanted it that way. It's very superficial, but it satisfies their curiosity the same way claiming everything is a conspiracy does for many people. We understand that others have motivations, and that we don't need to understand those motivations, and that's enough.

I am still not convinced that it is bad to believe in conspiracy theories. I mean, look, if you believe that humans were able to get to the Moon, that kind of implies that you can do anything if you make enough effort. It's a bit dangerous to think that, isn't it?

It implies no such thing.
Anything that is scientifically possible, according to correct theories, can be achieved to some degree with the appropriate means.
How is this dangerous?

Take fusion power (another huge engineering challenge): we may try and ultimately fail, but if we never try then we'd certainly have no chance of achieving it.

In real life, I insulted a friend by claiming that he was a part of the conspiracy because he claimed that airplanes exist and that he was in one. He, of course, asked me how did I thing he had got there if airplanes didn't exist, and I told him that I didn't owe him that answer and that he could prove dragons exactly the same way (seriously!). He said we were not friends any more and left. It's hard for me to figure out what was I thinking when I said that. Was I serious? Was I trying to be funny? I mean, now I cry when I remember that conversation.

That's terrible. No, you are not an exception, this is what being a conspiracy theorist does to people.
You should call or write your ex-friend and apologize.

But you don't have to be like that to be a conspiracy theorists. What do you think?

Of course being a conspiracy theorist will result in this. It's a nefarious philosophy that teaches you that people are dishonest, and you can't trust them. At its core it is predisposed to create conflict and distrust -- very much like most religion.

You might as well argue in favor of the virtues of Meth or Crack, since not *all* users become addicted.

The rare case where somebody will not become a complete asshole from being a conspiracy theorist is not a defense of it. Overwhelmingly, this is the result. And it has no positive value to compensate for that. It's false. It discourages scientific knowledge. It's socially and politically harmful. It makes people idiots.

I know that, I was referring to the case when one of the beams is obviously vertical (as on the photograph I've shown). Vertical lines don't appear to converge because of the perspective. How do you draw a cube? And there is a simple geometry behind that (vertical lines not appearing to converge because of the perspective).

Vertical lines converge due to perspective just like horizontal lines. Go look up at a tall building.
What matters is camera angle.

Looking UP at a building is not different from looking OUT down a road.
If you look perfectly DOWN at a road the lines will not converge, if you look perfectly OVER at a building the lines with not converge.

With a wide angle shot, you are looking OVER only at the center. You are looking DOWN at the bottom, and UP at the top.
In order to capture an image that large without having any horizontal or vertical tilt in view angle across the image, the camera would have to be as large as the subject (it would have to stretch from ground to clouds), or the camera would have to be infinitely far away with an infinite zoom.

Taking a picture of something small without any apparent perspective is easy, because the camera is about the same size as the object.
You can achieve a similar effect by getting really far away and zooming in optically.
You need to learn more about photography.

Don't blame me. I asked my physics teacher that question and she said she didn't know.

She should be fired. Is there any other teacher available?

Unless those two balls, in the moment they both touch the lever, are equally distant from the triangle in the middle, the force acting on the right ball is going to be different from the force the left ball applied to the lever when colliding with it, so the right ball can't go to the same height as the left ball, right?

The torque is different: https://en.wikipedia.org/wiki/Torque
The distance over which the energy is transferred is different for each ball.
The math works out to impart the same energy to the other ball as long as they are constrained in an immobile frictionless apparatus and all energy is transferred.
I can't explain this to you, though. It would take too long to draw the diagrams. You should ask a more competent physics teacher.

[teo123]

Rejecting the conspiracy theories as such on TFES forum helps in debating, but, to be honest, I still believe in them. I don't think I am closed-minded, I gave up my belief in the Flat Earth Theory.

After the reaction mass has exited the thruster, it will be moving at a constant velocity.
What do you call it when mass changes velocity? E.g. from the velocity of the rocket (the reaction mass inside the fuel tanks just sitting there) to the velocity of the emitted reaction mass speeding away from the rocket?
Answer: Acceleration.
Going from zero velocity relative to the rocket, to any other velocity, is acceleration, and that means a force is applied.
Do the math assuming that the reaction mass accelerates to its exiting velocity over 1 second (it's not instant, that's impossible and would require an infinite force), then you can figure out the force applied to the rocket body for that time.

I am a bit confused now. If it only accelerates while it's inside the tank, then the force isn't external, and, according to the Newton's first law, the tank can't accelerate, right?

It's very superficial, but it satisfies their curiosity the same way claiming everything is a conspiracy does for many people.

And how is just trusting those who are smarter than you, as you said I should, different?

It implies no such thing.
Anything that is scientifically possible, according to correct theories, can be achieved to some degree with the appropriate means.
How is this dangerous?

I don't know now. Many people say things like "If NASA can get to the Moon, I can do X."

That's terrible. No, you are not an exception, this is what being a conspiracy theorist does to people.
You should call or write your ex-friend and apologize.

Why should I? He is a meat-eater. Isn't that way worse than being a conspiracy theorist, even if you are wrong?
By the way, what do you think was the correct response to me comparing his claim of flying in an airplane with the claim of flying a dragon?

Vertical lines converge due to perspective just like horizontal lines. Go look up at a tall building.
What matters is camera angle.

I have never been at a tall building, and this is very counter-intuitive. Besides, the vertical sun rays don't appear parallel even when you look at them with an eye and not just with a camera. And I will show you my math that apparently contradicts it.

Suppose that your eye is at the (0,0,-1), the coordinates being in the format (x,y,z), and that the projection plane is the plane with the x-axis and y-axis (the blue one). Now, suppose you have the points A(-2,-2,1), B(-2,2,1), C(2,-2,1) and D(2,2,1). Obviously, the line through the points A and B and the line through the points C and D are parallel. Now, are their projections on the projection plane also parallel? Apparently, they are. The projections of those points are A'(-1,-1), B'(-1,1) C'(1,-1) and D'(1,1). I've picked up some numbers to make things obvious so that I don't have to deal with the equations. So, where is the error in my reasoning?

She should be fired. Is there any other teacher available?

Unlikely. I have won the school physics competition two years in a row with her as a mentor. Apparently, that doesn't make me rational.

The torque is different: https://en.wikipedia.org/wiki/Torque
The distance over which the energy is transferred is different for each ball.
The math works out to impart the same energy to the other ball as long as they are constrained in an immobile frictionless apparatus and all energy is transferred.

I knew about the torque (under the name "moment of force"). To me, it seems that the torque (being equal to the product of force and the distance from the centre) should be the same for the both balls. Doesn't the law of the lever, expressed as F1*d1=F2*d2, apply there?

[brimstoneSalad]

I'm not going to discuss the science anymore for the moment, because this is a more pressing issue:

Rejecting the conspiracy theories as such on TFES forum helps in debating, but, to be honest, I still believe in them. I don't think I am closed-minded, I gave up my belief in the Flat Earth Theory.

You believe them on faith, against evidence that conspiracies are generally untenable, and what should be enough evidence to tentatively trust the scientific establishment. This is closed minded.
And thus far you have been pretty closed minded to accepting the idea that this is a problem.

You believe them because you like them and they have not been proved wrong to your satisfaction (they have been proved wrong, but you are ignorant of the proof). This is the same position theists hold. It's ignorant, and it's harmful.

Some kind of agnosticism is acceptable; a positive belief is not.

It's very superficial, but it satisfies their curiosity the same way claiming everything is a conspiracy does for many people.

And how is just trusting those who are smarter than you, as you said I should, different?

Scientific methodology is inherently different to that of conspiracy theories and religion.
Don't just arbitrarily trust smarter people without regard to methodology.
Scientists are smarter than you are because of the methodology.

I don't know now. Many people say things like "If NASA can get to the Moon, I can do X."

That's their problem. NASA did go to the moon. If people take from that to mean they can fly off buildings, then they're idiots, and have not understood the effort NASA put in going to the moon. You can do anything that's physically possible IF you put in enough resources and time. It doesn't just mean you can succeed at any arbitrary task. Few people thought going to the moon was physically impossible; to the contrary, it was clearly possible based on physics, just the practicality was questioned, and the ability to do it with existing technology (new technology had to be developed).

Why should I? He is a meat-eater.

Somebody else doing something bad does not excuse your bad behavior.

Isn't that way worse than being a conspiracy theorist, even if you are wrong?

Maybe not. You underestimate the harm to society of conspiracy theories. The same mentality is behind most if not all religious and nationalistic hatred. You were condoning and perpetuating that mindset.

By the way, what do you think was the correct response to me comparing his claim of flying in an airplane with the claim of flying a dragon?

He probably should have punched you in the face, and then never spoken to you again. It was unacceptable for you to doubt his honesty of having been on an airplane: somebody who calls you a liar to your face (as you did to him) is not likely somebody you can converse with.

She should be fired. Is there any other teacher available?

Unlikely. I have won the school physics competition two years in a row with her as a mentor. Apparently, that doesn't make me rational.

No, it doesn't. The state of science education in your country is apparently inadequate. If you want to learn science, you'll need to study abroad, or online on your own.

Once you accept that believing these conspiracy theories is wrong and understand why science is methodologically superior, I can answer the science questions you asked.

[EquALLity]

He probably should have punched you in the face, and then never spoken to you again. It was unacceptable for you to doubt his honesty of having been on an airplane: somebody who calls you a liar to your face (as you did to him) is not likely somebody you can converse with.

Um...

Are you serious? He SHOULD HAVE punched him in the face?

I see, this is why you aren't opposed to Donald Trump's violent rhetoric...

[brimstoneSalad]

He probably should have punched you in the face, and then never spoken to you again. It was unacceptable for you to doubt his honesty of having been on an airplane: somebody who calls you a liar to your face (as you did to him) is not likely somebody you can converse with.

Um...

Are you serious? He SHOULD HAVE punched him in the face?

I see, this is why you aren't opposed to Donald Trump's violent rhetoric...

https://www.youtube.com/watch?v=1wcrkxOgzhU

That reaction was appropriate, and the courts agreed.

[teo123]

Scientists are smarter than you are because of the methodology.

And how do I know what methodology they use? Good methodology wouldn't give answers that apparently contradict the basic physics, right?

You underestimate the harm to society of conspiracy theories.

Well, trusting that people are honest also harms the society. They aren't honest. They tell you that food animals are treated humanely, that they live happy lives and that they desire to be eaten.

It was unacceptable for you to doubt his honesty of having been on an airplane

And what if he had claimed to have flown a dragon?

The state of science education in your country is apparently inadequate. 

Are more educated people less likely to believe in conspiracies? I don't know.

Come on! Let's discuss science! That's way more entertaining than discussing conspiracy theories.

[brimstoneSalad]

And how do I know what methodology they use?

It's called the scientific method; it's radically different from the methodology religion uses, and that conspiracy nuts use.



Conspiracy theories and religion function in the same basic way. They make assumptions, ignore evidence, or make up rationalizations to avoid addressing them. They do not make predictions, or when they do they are vague, or when they're precise they make excuses for them not being accurate. They are absolutely non-rigorous.

Science is very different. It's a rigorous methodology that works to control bias, and examine statistical probability of provisional claims based on the outcome of objectively measured and evaluated experimentation. False theories are demonstrated so and abandoned, and it is continually improved -- although not by people ignorant of the field, since they don't even understand what they're criticizing.

Good methodology wouldn't give answers that apparently contradict the basic physics, right?

And it does not, to anybody who understands basic physics. You've demonstrated above that you do not; you're fractally wrong about everything you think you know about science. Of course it doesn't make sense to you.

Well, trusting that people are honest also harms the society. They aren't honest.

False. Trusting that all people are honest would, but we don't have to: we can trust larger numbers of people who can all agree about something. One person can lie, and a few people can collude and lie, but as that number grows they all have to be telling the same lie, and they all have to be evil in order to do it; you simply can not get that many people together supporting something they know to be untrue.

The only thing that unites that many people behind an untruth is religion, and that's based on delusion -- these people are not being dishonest so much as they are ignorant (and intellectually dishonest to themselves). When they do knowingly lie, they also believe the lies they tell have a righteous purpose, and they're frequently caught in them when they do it.

Your ignorance of human psychology and social systems is as pervasive as your ignorance of basic physics: this is not a claim you can understand or make. Spend some time, as I asked you to do, studying actual conspiracy theories. They're carried out by small numbers of people, and still prone to whistle blowers.
The biggest secret keepers in the world are government, like the NSA, and we still have Snowdens blowing the lid on those secrets -- when it happens, it's out. The entire scientific community doesn't deny it, and the government can't even deny it: they try to find the traitors and prosecute them.
The response is night and day compared to insane conspiracy theories that people reject for good reason: because they know better.

They tell you that food animals are treated humanely, that they live happy lives and that they desire to be eaten.

Not even the industry maintains that animals want to be eaten, that's insane beyond typical propaganda and industry delusion. The notion that they are treated humanely is a matter of their "opinions": largely, the people who work in this industry are delusional, and suffering from cognitive biases. And the evidence to the contrary is well propagated and pretty uncontroversial. We're basically dealing with a religion of carnism, and with people whose jobs rely on them not believing what's apparent to so many.

You can't compare transparent propaganda and industry bias to conspiracy theories. How this works is common knowledge for people remotely familiar with the issue.
What you're dealing with in propaganda are usually matters of framing and exaggeration.
And even then, in extremes where they do outright lie, their internal memos get leaked (as they did with big tobacco), an when they are shown to be liars that spreads around. It's taking time, because people want to believe the lie, but it doesn't in any way resemble the conspiracy theories you've been advocating.

It was unacceptable for you to doubt his honesty of having been on an airplane

And what if he had claimed to have flown a dragon?

Then you should have assumed he was joking, or been concerned for his mental health. I should not have to explain why claims of flying in an airplane and flying on a dragon are different.

Are more educated people less likely to believe in conspiracies? I don't know.

Quite a bit less likely, particularly in the hard sciences. The "social sciences" (which are called science, but are often not science) are filled with conspiracy theories (like intersectionality, and the patriarchy), though not everybody in the social sciences believes in them. It's a religious dogma, and it's transparent if you evaluate it with proper methodology.

Come on! Let's discuss science! That's way more entertaining than discussing conspiracy theories.

When you can understand and explain to me the difference in somebody claiming to have been on an airplane, and having flown on a dragon, I can explain the science to you. If you can't understand that, then there's no point in going into the science.