Your Day

OccultHawk · 08-24-2019, 10:47 PM

Quote:

Originally Posted by Doug McClasky

Like I'm basically asking if it's a difference in "philosophy" or if there's a measurable difference in equations. Like, is a thing that's not moving in mid-air because it's reached its zenith mathematically different from something that is sitting still simply because of gravity and air pressure that are working against each other but keeping said thing still?

I think that’s a great question because it gets into why is there a different term for something just because the amount of time in that situation is negligible from a human perspective.

OccultHawk · 08-24-2019, 10:51 PM

Quote:

Originally Posted by Pet_Sounds

Yeah, there's a difference in equations. Calculus was invented basically for this question. You need an "open interval" (which can be arbitrarily small) of time around a given point to discuss instantaneous rate of change, and the difference comes down to the behaviour of the object in that open interval as it approaches the point you're interested in. In the case of the ball in mid-air, its motion changes immediately before and after the point in time at which its velocity is zero; the ball on the ground doesn't move at all.

Sorry I'm not explaining this very well, it's hard without math.

But the way we understand time philosophically does seem to influence the way physicists describe the phenomenon.

Pet_Sounds · 08-24-2019, 10:58 PM

Time is what a clock measures.

OccultHawk · 08-24-2019, 11:07 PM

Quote:

Originally Posted by Pet_Sounds

Time is what a clock measures.

Couldn’t an extraordinarily precise clock measure the amount of time a ball in mid air isn’t moving so therefore if physicists wanted to describe it as such it could be called at rest same as me sitting on a sofa because it’s just a matter of time before my body weight is going to win out even though at the moment the forces are (almost) equal not allowing me to fall through?

Pet_Sounds · 08-24-2019, 11:11 PM

Quote:

Originally Posted by OccultHawk

Couldn’t an extraordinarily precise clock measure the amount of time a ball in mid air isn’t moving so therefore if physicists wanted to describe it as such it could be called at rest same as me sitting on a sofa because it’s just a matter of time before my body weight is going to win out even though at the moment the forces are (almost) equal not allowing me to fall through?

No, no matter how small your interval of measure is the ball in midair will always exhibit some movement in that interval.

EDIT: To be clear, we're talking about Newtonian physics here.

The Batlord · 08-24-2019, 11:16 PM

Quote:

Originally Posted by Pet_Sounds

Yeah, there's a difference in equations. Calculus was invented basically for this question. You need an "open interval" (which can be arbitrarily small) of time around a given point to discuss instantaneous rate of change, and the difference comes down to the behaviour of the object in that open interval as it approaches the point you're interested in. In the case of the ball in mid-air, its motion changes immediately before and after the point in time at which its velocity is zero; the ball on the ground doesn't move at all.

Sorry I'm not explaining this very well, it's hard without math.

So the "point of non-zero acceleration" is simply a point in whatever relevant bigger equation that relates to the equation that describes the behavior of the object before the "point of non-zero acceleration" and how that relates to the equation describing the behavior of the object after the "point of non-zero acceleration"? [i.e. the ball was thrown (before point of non-zero acceleration), the ball reached its height (point of non-zero acceleration), and the ball fell (after point of non-zero acceleration)].

That sounds like a truism to me, and if that's correct is there an equation or "family" of equations or whatever to describe that "point of non-zero acceleration" or is that point simply a plot to point in the greater equation? Like that point of non-zero acceleration is constant no matter the equation and does not have to be calculated, or the nature of the greater equation of the "rise and fall of the ball" will dictate what the point of non-zero acceleration will be?

Quote:

Originally Posted by Pet_Sounds

Time is what a clock measures.

But I mean time is a thing we as humans can not measure because we do not have an organ to measure it realistically, in the same way that we use an imperfect two dimensional measuring organ (the eye) to measure three dimensional space. It's not perfect, does not make any sense as a measuring instrument if you look at its performance too closely, but it's good enough for government work. The brain measures time by memory and does so imperfectly but it works as well as we can hope. A clock measures time but we use the brain to interpret what that measurement means and we do it imperfectly which is why we need math to fix our ****.

It sounds to me that this calculus equation you're talking about with nonzero acceleration is our way of breaking down time in relation to a certain instance of movement in a way that makes it make sense in as best a way as we can.

The Batlord · 08-24-2019, 11:21 PM

Quote:

Originally Posted by elphenor

nerds

shut up, goth boy

Pet_Sounds · 08-24-2019, 11:22 PM

Quote:

Originally Posted by Doug McClasky

So the "point of non-zero acceleration" is simply a point in whatever relevant bigger equation that relates to the equation that describes the behavior of the object before the "point of non-zero acceleration" and how that relates to the equation describing the behavior of the object after the "point of non-zero acceleration"?

That sounds like a truism to me, and if that's correct is there an equation or "family" of equations or whatever to describe that "point of non-zero acceleration" or is that point simply a plot to point in the greater equation?

In this case, position is given by a quadratic equation in one variable (i.e. a parabola) velocity is given by its first derivative (i.e. a possibly sloped straight line) and acceleration is given by its second derivative (i.e. a level straight line).

Quote:

Originally Posted by Doug McClasky

It sounds to me that this calculus equation you're talking about with nonzero acceleration is our way of breaking down time in relation to a certain instance of movement in a way that makes it make sense in as best a way as we can.

Yeah, it's a model developed by Newton.

OccultHawk · 08-24-2019, 11:25 PM

Quote:

Originally Posted by Pet_Sounds

No, no matter how small your interval of measure is the ball in midair will always exhibit some movement in that interval.

EDIT: To be clear, we're talking about Newtonian physics here.

ok

I think (know actually) everything is either moving toward or away from the center of the earth just far more slowly than the midair ball. That’s an example of how philosophy and language informs science.

OccultHawk · 08-25-2019, 12:06 AM

Quote:

In this case, position is given by a quadratic equation in one variable (i.e. a parabola) velocity is given by its first derivative (i.e. a possibly sloped straight line) and acceleration is given by its second derivative (i.e. a level straight line).

Are these examples?

If not can you find a graph?

08-24-2019, 10:58 PM	#63943 (permalink)
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