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What is something that sounds 100% true but is actually 100% false?
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this post was submitted on 14 Jul 2023
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Asklemmy
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If an object isn't pushed by any force, it'll stop moving. (It'll actually keep moving at the same speed).
Not in real life though. Only in Highschool physics class.
That's because of friction and air resistance which are still forces. Repeat the same experiment in outer space where there's no atmosphere or stuff in the way and you won't see that
There's even things like ion engines that take advantage of that by producing tiny amounts of thrust but run over long amounts of time to build up quite a bit of speed
https://en.m.wikipedia.org/wiki/Ion_thruster
Having taken not only Highschool physics but also university physics courses I know that.
That doesn’t change that for most people in most environments the sentence “if you don’t put in power continuously it’ll stop” or whatever the wording was is, in fact, true.
It becomes false only if you change the context, but I would argue, if you know all the facts and scenarios, that’s willful misunderstanding.
Ngl saying it isnt pushed vs isnt acted on by a force are entirely difference scenarios, a push is a subset of forces (as im sure you know with your uni courses right ;)
Else newtons laws would be incorrect on a macro scale, which to say at the least would be... concerning
Physics is about nothing but real life
A statement so general that it is useless.high school physics does so many simplifications that it’s only about very specific experiments in real life, but is generally not very accurate.
Statistical approximations are a large part of complex systems, such as the summation of billions of forces of atoms.
Id argue given the insane ammount of moving parts, a simplication as easy to understand as Newtonian mechanics is extremely accurate, at least compared to the limited input data
We’re talking here about the consideration of friction and air resistance…
Oh my I really overestimated your standpoint there, your argument is simply the existence of eletrostatic forces? Cause I can gaurentee the original comment takes that into consideration, under the term 'forces' - highschool or not such is true until the limits of Newtonian mechanics.
Simplified, if something has no forces acting on it, it also has no electrostatic resistance (aka friction), and will follow newtons 2nd law - remain at rest or in motion, as the original comment stated.
I thought you were debating why the comment didnt take quantum effects into consideration lol
Oh my, the level to which nitpickers will go… my point is that the “false” statement from OC is in fact true for most people in their daily life. Try to ride a bike to understand what they experience.
It’s not even necessary to qualify that statement, unless you are discussing situations on earth vs situations in space. That’s why OC is false imo, because he takes a common understanding out of its context.
The statement is false in space travel and planet mechanics, which most people don’t do daily, and don’t need to consider, or if you look at it from the point of the physics book, which in this case conveniently ignores the situation most people are in most of their lifes: on earth where friction and air resistance are a reality.
My whole point is this context shift is willful misunderstanding.
Tbh Id argue the opposite on the nitpickyness, as on a bike you feel forces - kinda obviously. The space example only is used (although yes uncommon) because it has minimal forces.
Supprisingly enough if you have forces applying to you, you are an object under force (and such wont be going a constant speed - woah who knew), and so the original comment would not apply
Long story short quit trying to call them out to sound smart, you're just making an idiot out of yourself
As a high school physics teacher, if this is the hill you're willing to die on, then you neither understood the content in your high school physics class nor your university physics class. Newton's 2nd law is generally accurate in most scenarios even without simplifications.
Like me stopping to peddle my bike?
Yes, like you stopping to peddle your bike...
A simple force diagram and application of newton's 2nd law predicts the bike should accelerate to the left while it's velocity is towards the right. This means the bike should slow down.