|
Walter & Group...
[GH] I failed to place the attachment containing Ally Gowans' message on fly-casting mechanics/physics in our last message.
Here is the message:-
Hi Gordy,
This was from Walter:
"The line has to have sufficient energy and energy is force times distance. I can apply a tremendous amount of force for a millimeter and get no loop or I can apply relatively little force over a large distance and get a loop."
The highlight is mine.
Energy is not force times distance, that quantity is known as “Work” or “work done”. Energy possessed by a moving line is a combination of kinetic and potential energy, kinetic by virtue of its velocity and potential by virtue of its position.
Since force and acceleration are proportional, if the mass is small and the force is large enough even over a short distance an object can in theory be made to travel very fast. I think that the point Walter is trying to make here is simply that given constant mass and constant linear acceleration, terminal velocity is proportional to the amount of time that the force is applied. This requires a straight line path and constant force application neither of which is likely to be delivered by a rod tip which in practice which moves in an arc pulling a line that is constantly changing its position relative to the rod tip.
There is also merit in considering the rod tip path as part of a semi-circle which allows consideration of the sinusoidal relationship between rod tip and tangential line velocity. Since there are a huge number of variables involved in line motion there is no practical merit in the fine mathematical detail but it is very useful to have a qualitative understanding of the complex relationship between the rod tip and the line.
Artificial definitions between rotational and linear movement at the handle end of a flexible lever make no sense to me.
Best regards,
Ally Gowans
|