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Constant Acceleration
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- Paul Arden
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Constant Acceleration
Hi folks,
I know we had a discussion on this before but the board search function ignores common words such as acceleration
When I look at the acceleration graphs I see a curve not a straight line. To get “constant acceleration” the beginning of the cast is ignored. Now one could say it’s because we are human. Or perhaps it’s because we need to start the stroke slowly?
Anyway I regularly hear instructors talk about the need for constant acceleration. What do the members of this forum think about this?
Many thanks,
Paul
I know we had a discussion on this before but the board search function ignores common words such as acceleration
When I look at the acceleration graphs I see a curve not a straight line. To get “constant acceleration” the beginning of the cast is ignored. Now one could say it’s because we are human. Or perhaps it’s because we need to start the stroke slowly?
Anyway I regularly hear instructors talk about the need for constant acceleration. What do the members of this forum think about this?
Many thanks,
Paul
Re: Constant Acceleration
Depends what you mean by constant acceleration. In my experience, it means whatever the speaker wants it to. I don’t use it.
Regards
Vince
Regards
Vince
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Re: Constant Acceleration
I can't remember what my graphs showed but I think it didn't matter and rarely occurred. (We are talking about constant acceleration of the line, aren't we?)
To get around that annoying search "feature", type this into a google search: acceleration site:http://www.sexyloops.co.uk/theboard
Cheers,
Graeme
To get around that annoying search "feature", type this into a google search: acceleration site:http://www.sexyloops.co.uk/theboard
Cheers,
Graeme
FFi CCI
Re: Constant Acceleration
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Re: Constant Acceleration
Yeah... this should be fun!
I think the term is ambiguous at best, and probably not what most non-physicists think it means... and I am not a physicist so I'll let them try to explain.
But... I think the curve should be a curve, not a straight line... and I doubt, even with rotation and leverage, that a human is capable of achieving "constant" acceleration of the line. Well, not throughout the whole stroke. The importance of the haul to just maintain a constant speed seems to prove it?
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Re: Constant Acceleration
Hi Paul
"Constant acceleration" can only be constant in one of two ways -
My acceleration plots that Graeme referenced are unfortunately how Tracker calculates them, which yields increasingly more jittery charts the higher the derivative represented. They can be simplified in the reader's mind to cut through the jitter.
This graph from the Wikipedia page on Jerk may provide some perspective on the dynamics relationships:
NOT a physicist either, nevertheless trying to explain.
All the best,
Dirk
"Constant acceleration" can only be constant in one of two ways -
- The acceleration remains constantly the same magnitude and its time plot (with time on the horizontal axis) is a straight horizontal. The resulting velocity plot is a straight slope
- The acceleration increases/decreases at a constant rate and its time plot is a straight slope. The resulting velocity plot curves like a parabola
My acceleration plots that Graeme referenced are unfortunately how Tracker calculates them, which yields increasingly more jittery charts the higher the derivative represented. They can be simplified in the reader's mind to cut through the jitter.
This graph from the Wikipedia page on Jerk may provide some perspective on the dynamics relationships:
NOT a physicist either, nevertheless trying to explain.
All the best,
Dirk
Re: Constant Acceleration
Greetings.
One recent thing related to this is Graeme's brilliant "top ferrule"-exercise, which I think provides an external cue for constant acceleration. Due to the good ole \(F=ma \rightarrow a=F/m\), if the mass \(m\) stays constant, a constant force \(F\) will yield constant acceleration \(a\). In Greame's exercise, the student needs toPaul Arden wrote: ↑Thu Sep 01, 2022 10:15 am Anyway I regularly hear instructors talk about the need for constant acceleration. What do the members of this forum think about this?
This yields constant acceleration as it implies a constant force being applied to the line. To see this, consider having the rod in place and pulling the line with one hand, then keeping your line hand static once you reach a certain force level, that is, constant force: this will place a bend at a certain location in the rod, and the bend will stay the same as long as the force stays constant. Therefore, a "fixed bend" implies constant force and therefore constant acceleration.put a bend in the rod at the top ferrule and keep it there as long as you can
Re: Constant Acceleration
I'm going to stick this here and see if people can figure out why I'd make this statement:
A constant acceleration* will cause a tailing loop.
*constant in terms of the definition above such that the velocity increase is perfectly linear.
James
A constant acceleration* will cause a tailing loop.
*constant in terms of the definition above such that the velocity increase is perfectly linear.
James
Re: Constant Acceleration
What are we accelerating James? The line or some part of the rod?
Cheers,
Graeme
Cheers,
Graeme
FFi CCI
Re: Constant Acceleration
Here you go:
https://www.sexyloops.com/articles/perfectloop.shtml
Quest for the Perfect Loop
by Bruce Richards
"- The rate of acceleration of the rod butt must be as close to the same at the beginning of the stroke as it is at the end. Yes, the rod will be going much faster at the end than the beginning, but the rate of acceleration should be constant in getting the rod from slow to fast. I know this goes counter to what many have said and written, and even to what many of us think we do, but ALL the best casters we've analyzed had very constant acceleration, regardless of what they thought they were doing."
Torsten.
https://www.sexyloops.com/articles/perfectloop.shtml
Quest for the Perfect Loop
by Bruce Richards
"- The rate of acceleration of the rod butt must be as close to the same at the beginning of the stroke as it is at the end. Yes, the rod will be going much faster at the end than the beginning, but the rate of acceleration should be constant in getting the rod from slow to fast. I know this goes counter to what many have said and written, and even to what many of us think we do, but ALL the best casters we've analyzed had very constant acceleration, regardless of what they thought they were doing."
Torsten.