We can perceive position, velocity, acceleration, jerk

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Discussion Overview

The discussion revolves around human perception of motion, specifically the ability to perceive position, velocity, acceleration, jerk, and potentially higher-order derivatives like jounce. Participants explore the sensory mechanisms involved in these perceptions and question the limits of human capability in recognizing such changes in motion.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants suggest that humans perceive position through established reference points and velocity through changes in position.
  • Acceleration is perceived as a change in velocity, while jerk is noticed as a change in acceleration.
  • There is a question about whether humans can perceive jounce or higher-order derivatives, with some expressing uncertainty about the limitations of human perception.
  • One participant describes how sensory experiences, such as wind and vibrations, contribute to the perception of velocity and acceleration, emphasizing the role of visual cues.
  • Another participant notes that while we may feel jerk, it is often interpreted through other sensations, and there may be a limit to how many derivatives can be perceived or considered in reasoning.
  • There is a discussion about the simplification of motion concepts in physics, with some arguing that humans rely primarily on position, velocity, and acceleration, while considering jerk as a simplification.

Areas of Agreement / Disagreement

Participants generally agree that there are limits to human perception of motion and that simplifications are often necessary. However, there is no consensus on the extent to which higher-order derivatives can be perceived or the implications of these perceptions.

Contextual Notes

Participants express varying views on the sensory mechanisms involved in perceiving motion and the potential limitations of human perception, indicating that the discussion is nuanced and complex.

DarkFalz
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We can perceive position by establishing a reference point
We can perceive velocity by noticing a change in position
We can perceive acceleration by noticing a change in velocity
We can perceive jerk by noticing a change in acceleration

Can humans also perceive jounce or any higher order derivative of position? I'm trying to understand if it is actually possible or, if not, it is impossible due to human limitations?

Thanks in advance
 
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To think about this you need to consider how the body gives the sense of those things. i.e. what does it feel like.

For instance - we do not "feel" our velocity by noting the change in position so much as from the wind in our faces and the vibration/sensation of movement.
The relative positions of things around us provide a clue though, especially for low speeds where the sense is sometimes fooled by small motions in the surrounding objects.

We feel accelerations as a pressure or a push, similar to gravity.
Motion simulators exploit this by tilting the simulator to simulate horizontal acceleration.
As before - visual cues reinforce this sensation (the simulator will also play a movie of an accelerating POV).

So what would a low continuous jerk feel like? - remember that this is the technical term not the common use word.
Well... it would feel like the direction and/or strength of gravity is slowly changing, but at a constant rate.
You'd probably spot that if you were looking for it, though you may interpret it as something else, like being slowly tilted back in your seat or as some viscous fluid impeding your limbs, depending of the visual cues.
Usually you can tell when you've made a transition between low and high acceleration though - especially if it is sudden.

You should be able to continue the reasoning to higher orders.
 
Simon Bridge said:
To think about this you need to consider how the body gives the sense of those things. i.e. what does it feel like.

For instance - we do not "feel" our velocity by noting the change in position so much as from the wind in our faces and the vibration/sensation of movement.
The relative positions of things around us provide a clue though, especially for low speeds where the sense is sometimes fooled by small motions in the surrounding objects.

We feel accelerations as a pressure or a push, similar to gravity.
Motion simulators exploit this by tilting the simulator to simulate horizontal acceleration.
As before - visual cues reinforce this sensation (the simulator will also play a movie of an accelerating POV).

So what would a low continuous jerk feel like? - remember that this is the technical term not the common use word.
Well... it would feel like the direction and/or strength of gravity is slowly changing, but at a constant rate.
You'd probably spot that if you were looking for it, though you may interpret it as something else, like being slowly tilted back in your seat or as some viscous fluid impeding your limbs, depending of the visual cues.
Usually you can tell when you've made a transition between low and high acceleration though - especially if it is sudden.

You should be able to continue the reasoning to higher orders.

But there must still be a limit to how many derivatives we can perceive or take into account in our reasoning/thinking, because we are limited. Do we rely mostly on position, velocity and acceleration and consider a constant jerk to simplify things?
 
That is correct: there are many limits on our abilities.
You can continue the reasoning provided to discover where the limit lies in this case.

Do we rely mostly on position, velocity and acceleration and consider a constant jerk to simplify things?
It is difficult to know what you are asking here.

We rely on our sense of jerk (i.e. and for want of a better term) every day - almost every change in our motion involves non-constant accelerations.
Thus we are evolved to unconsciously account for a lot of non-linear processes: it is where a lot of our intuitions about motion come from.

The term "jerk" refers to a mathematical concept - invented to make thinking about motion easier, and easier to talk about... so it is a simplification in that sense.

When we do physics, as opposed to just walking down the street, we ask ourselves what is the least we need to know about something to still know everything about it.
The theory which gives the largest description with the least input is considered "simpler". This is why Newtonian Gravitation is simpler than Ptolemies Epicycles - they both work, but Newton's approach requires less foreknowledge and is more general.

Position, velocity, and acceleration (usually by way of forces), are all we need to know everything about the classical motion of a body.
These things are the simplification that our senses can only get through a more complicated series of impressions.

The bottom line is, in your work, you should "rely on" whatever it is that needs the least maths, and still gets you the right answer.
 

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