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objects fall backwards when dropped from the hand Options
Amarillide
Posted: Monday, May 25, 2020 6:16:23 AM
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Hi there scientific bright minds!
 
Can someone please explain to me the phrase in bold?

Aristotle believed that heavier objects fall faster than lighter objects (Physics Book IV). What a dunce. But then Aristotle had many good and bad ideas. Thanks to Galileo and Newton, we understand now how gravity doesn’t play favourites, although many thought as Aristotle did until Newton’s 1687 Principia (I’ve held the original from the British Library in my hands). Some still think as Aristotle did that moving objects fall backwards when dropped from the hand, unbothered by a simple demonstration to the contrary.


I am not able to find any reference online, but I am very bad at Science... maybe that's why... On the top, I am not a native speaker, so maybe there is something more I am missing, but I am not able to figure out the meaning of "falling backwards"

Apologies in advance for the possible extreme idiocy of my question...


Ama

thar
Posted: Monday, May 25, 2020 6:37:24 AM

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I think this about not having a concept of momentum.He believed there were two different types of motion:
Violent motion where you push or throw something and it goes forwards.
Natural motion where you drop something and its natural motion is to return to its fellow matter (rocks towards the earth, smoke towards the sky).

I am not entirely sure where the 'backwards' comes in, but his ideas may lead to the deduction that however fast an object is moving before you drop it, it doesn't keep going forward, it just drops out of the back of your hand and falls directly down with natural motion.
If it comes out of the front of your hand that is a throwing action - violent motion and that is why it flies forward before falling to the ground.

That is what I read into it. Like you I can't see anything about falling backwards. So I think this is the idea of not falling forwards (if it is dropped) even it it was moving forwards. But I may be completely wrong.
Amarillide
Posted: Monday, May 25, 2020 7:19:05 AM
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Hello Thar!
Nice to "see" you here!

Your guess about the hand interrupting a movement is something I didn't think (of course... I've said it earlier that I am an avowed science-incompetent!), but, as you say, it still does not fit with the idea of "falling backwards." 

I think I am going to send a quick email to the author to clear up this doubt. Let's see...

Then, of course, I'll get back here!

Xx
Ama







Amarillide
Posted: Monday, May 25, 2020 3:02:36 PM
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If a moving object (a man walking, a bird, an airplane) something that moves forward drops an object, according to the Aristotelian theory that object, that is falling by his idea of natural motion, will not be affected from the movement forward and had no forward velocity, so it would fall backward, unaffected. In reality it is affected by the same forward movement of the object that drops it and it will follow a parabolic path.

I am already sweating.
I may have missed something, but I hope you'll get my attempt to be scientific! Brick wall  
Ama
Amarillide
Posted: Tuesday, May 26, 2020 6:41:44 AM
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Amarillide wrote:
If a moving object (a man walking, a bird, an airplane) something that moves forward drops an object, according to the Aristotelian theory that object, that is falling by his idea of natural motion, will not be affected from the movement forward and had no forward velocity, so it would fall backward, unaffected. In reality it is affected by the same forward movement of the object that drops it and it will follow a parabolic path.

I am already sweating.
I may have missed something, but I hope you'll get my attempt to be scientific! Brick wall  
Ama


Sorry Thar, yesterday I was extremely tired... and you can tell from the errors. Maybe such errors (given the object) don't help my attempt to explain. 
I'll try to put it down nicely.

Let's put there is an airplane that drops an object.
According to Aristotle, that object would not be affected from the forward movement of the airplane, it would not have any forward motion influencing his "natural motion" (as Aristotle calls it) towards the ground, so it would fall "backward" (backward compared to the airplane that keeps going forward).
Actually, according to our ("our"Whistle ) knowledge of Physics, it is influenced by the forward movements, and therefore it would follow a forward parabolic trajectory while it falls towards the ground

I would say that it was not that immediate unless for someone that's extremely familiar with Physics. But as I already said I am not a good way to judge, when it comes to science, if something is understandable.

Bye,
Ama
Kirill Vorobyov
Posted: Wednesday, May 27, 2020 8:03:56 AM

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Hello, Ama and Thar!

I did study physics for a few years, but we began with Newton, so my knowledge of Aristotle's physics seems to be much worse than Thar's. But I think you both are right in your interpretation of the sentence.

One thing I wanted to note though is that the idea itself of natural motion remains valid, in essence. Only in modern physics it is not called as such. They call it fundamental interaction.

E.g. gravity is one of the fundamental interactions. Planets rotate around the Sun and will do so infinitely long being driven by "gravity" (in modern terms). But that movement could as well be interpreted as planets' "natural motion". What Aristotle may have missed (again, I didn't study his works) was that a stone's natural motion is toward the center of Earth, not to the place it had been lying before somebody took it up.



Drag0nspeaker
Posted: Wednesday, May 27, 2020 12:15:36 PM

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thar's first idea of "momentum" is what is described in your second quote.

And your explanation of it (the aeroplane dropping the object) is good.


The difficulty in understanding (from my viewpoint) is caused by the way the first quotation is worded.
"Some still think as Aristotle did that moving objects fall backwards when dropped from the hand."

That is not true - what Aristotle believed was that an object falls exactly downwards (not 'backwards') when dropped - not being influenced by the previous forward motion.
It's not that the object falls backwards - it is the person who dropped it continues to move forwards.

The "true" Newtonian datum is that the object continues to move forwards - and also moves downwards.
This makes it fall in a curve.
Amarillide
Posted: Wednesday, May 27, 2020 2:38:59 PM
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Drag0nspeaker wrote:



The difficulty in understanding (from my viewpoint) is caused by the way the first quotation is worded.
"Some still think as Aristotle did that moving objects fall backwards when dropped from the hand."



...yes, it was a bit too coincise! I had to ask the author because I could not work it out, and I don't know anything of Physics...

Well.. all's well that ends well!

Ama
Kirill Vorobyov
Posted: Thursday, May 28, 2020 5:57:32 AM

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Drag0nspeaker wrote:

That is not true - what Aristotle believed was that an object falls exactly downwards (not 'backwards') when dropped - not being influenced by the previous forward motion.


Oh, so he did get it right in terms of the natural motion. He only didn't sum velocities. If so, this is strange, as the fact that velocities sum up is rather easily and commonly observed.
Amarillide
Posted: Thursday, May 28, 2020 5:17:22 PM
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Kirill Vorobyov wrote:
[quote=Drag0nspeaker]
If so, this is strange, as the fact that velocities sum up is rather easily and commonly observed.


... well, apparently not for everyone!... For example if you asked me before... well I am not sure I wouldn't have given an Aristotelian answer!Anxious

Bye!
Ama
Amarillide
Posted: Thursday, May 28, 2020 5:18:04 PM
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Kirill Vorobyov wrote:
[quote=Drag0nspeaker]
If so, this is strange, as the fact that velocities sum up is rather easily and commonly observed.


... well, apparently not for everyone!... For example, if you asked me before this... well I am not sure I wouldn't have given an Aristotelian answer!Anxious

Bye!
Ama
TMe
Posted: Friday, May 29, 2020 12:27:34 AM

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Many forces act on a moving or falling body which affects its movement.


https://www.youtube.com/watch?v=E43-CfukEgs
Amarillide
Posted: Friday, May 29, 2020 12:55:23 AM
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Joined: 2/13/2020
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TMe wrote:
Many forces act on a moving or falling body which affects its movement.


https://www.youtube.com/watch?v=E43-CfukEgs


yes... that's the first time man had a proof after Galileo. I know all of you know but it is always nice to see men on the moon:

https://www.youtube.com/watch?v=KDp1tiUsZw8

stevejones1981
Posted: Tuesday, September 15, 2020 9:23:06 AM
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Aristotle said objects move straight down when dropped. So, if you face in the direction that the Earth is moving, then everything that falls ought to drop behind you because the Earth would have moved forward while it was falling straight down.
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