casting a bamboo rod

[Torsten]

Hi,

Acceleration in regards to change in speed is a scalar quantity since speed is a scalar.

That's IMHO not existing (at least regarding physics/mechanics), AFAIK even a test question, e.g. here
https://brilliant.org/wiki/is-accelerat ... -of-speed/

Is this true or false?
Acceleration is the rate of change of speed.

The statement is false.

Explanation:

Acceleration is defined as the rate of change of velocity. Velocity is a vector, which means it contains a magnitude (a numerical value) and a direction. So the velocity can be changed either by changing the speed or by changing the direction of motion (or both). Therefore, it may be possible that the speed is constant, but the velocity is changing because the direction is changing. In this case, acceleration will be non-zero and equal to the rate of change of velocity.

It is a general misconception that rate of change of speed is equal to the magnitude of the rate of change of velocity. However, this is not true in all cases. Consider uniform circular motion: in the case of a uniform circular motion, the particle moves on a circular path with uniform speed. The speed remains constant, but the direction of motion is continuously changing. Due to change in direction of motion, acceleration is non-zero. This acceleration is toward the center of the circle and known as centripetal acceleration.

In general, acceleration can be resolved into two components. One component, which is parallel to the velocity, is known as tangential acceleration. This component changes the speed of the particle and is equal to the rate of change of speed. The other component of acceleration, which is perpendicular to velocity, is known as normal acceleration. This component is responsible for changing the direction of the velocity.

Velocity is the rate of change of displacement, while speed is the rate of change of distance. In other words, velocity is the rate of change of the shortest distance moved by a body from the final position to the initial position, while speed is the rate of change of the total length of the path traveled by a certain body.

If Paul writes "The primary purpose of the haul is to increase line speed." that would be fine IMHO.
(you still need to keep in mind that an influence on the rod bend / tip trajectory is possible)

I definitely think that the effect on tip path as the rod is unloading needs more study. Potentially this is really one of the keys. If the haul is aggressive enough then it will be controlling the unloading of the rod, straightening the tip path. Grunde pointed this out to me in Scotland but also said it needs more study and isn’t certain yet.

That's likely, I'd think in many cases the haul would flatten the overall acceleration path of the line. Decreased bend is possible if you consider the same kinetic energy of the line; longer acceleration path, less force for the same work.

Greetings,
Torsten

[Lasse Karlsson]

Hi Lasse,

I think that’s because acceleration has a direction component.

Ok well that’s interesting. I’ve only seen the mini circles perhaps a dozen times. In my mind I imagine the tip slightly rising at the conclusion of the haul, occurring just prior to the rod tip departing from the line trajectory, pre RSP. But it could also be a disconnect between the end of the haul (line is faster than the rod tip) and the rod tip continuing to accelerate as the rod continues to unload.

How do you make them happen without hauling?

Cheers, Paul

Hi Paul

Yeah, but we use a simple pulley in the rod, I move the line hand 1 meter, the line outside the rodtip moves 1 meter in the direction it can move.

Take your MPR, and do some slow casting. Move the rodtip as straight as possible and make trailing loops, when you get DN's, slow even more down and go tighter. When the loop starts tilting over, you should get circles. Same goes with a normal flyline in the field.

Cheers
Lasse

[Walter]

Now I’m curious.

What does one call the rate of change of speed with respect to time in physics?

English is an interesting language. I’m sure that this is true in other languages as well but I’m not an expert. A word can have the same spelling and pronunciation but have multiple meanings. They’re called homonyms. I can use a lifting device called a crane to lift a box with a large bird also known as a crane. Both uses of the word crane are correct.

The Oxford dictionary defines acceleration as the increase in the rate or speed of something. Direction definitely isn’t required in that definition. It even provides an interesting example of usage “the acceleration of the industrial process” so we can see that even speed isn’t a requirement for acceleration . It does make note that in physics it’s the rate of change of velocity per unit time so we know that in physics it is expected to be a vector quantity consisting of both a magnitude, commonly referred to as speed, and a direction, commonly referred to as a direction.

Lasse’s original statement was that “hauling accelerates the line directly”. Mathematically, we say that a direct variation between two variables shows both variables changing the same way, meaning both variables are increasing or both are decreasing. the variables in this case being line speed and hauling speed. I’m pretty sure that if I increase hauling speed it will result in line speed increasing (accelerating as per Oxford definition), not decreasing which would be an inverse relationship.

[VGB]

I can’t wait to run this thread through a spelling and grammar check in the morning. There must be a level of trivia that has been omitted.

[Walter]

I can’t wait to run this thread through a spelling and grammar check in the morning. There must be a level of trivia that has been omitted.

I tried running it through an ai detector. It said “no I detected”.

I’m curious what grade reading level you’ll get.

[VGB]

ai detector. It said “no I detected”.

Ai detector?

[Paul Arden]

Are we talking about the same thing Lasse, instead of a dolphin nose a full circle the size of the DN?

IMG_1477.jpeg (40.02 KiB) Viewed 139 times

What I’m unsure about is if there is a DN behind the circle.

Cheers, Paul

[Stoatstail50]

Hauling accelerates the line directly.

This statement is false.

Being a simple soul, I’m slightly confused now….is Torstens statement true or false ?

Did something happen to f=ma?

[Lasse Karlsson]

Are we talking about the same thing Lasse, instead of a dolphin nose a full circle the size of the DN?

IMG_1477.jpeg

What I’m unsure about is if there is a DN behind the circle.

Cheers, Paul

It wouldn't be the first, or the last time we where talking about different things But from your drawing I suspect we are in fact talking about the same thing.

From what I see making them, it's starts as a DN and then turns into a circle.

Cheers
Lasse

[Paul Arden]

Hi Lasse, my MPR is in Hungary. Can you shoot some video please? It would be interesting to know to mechanism.

Thanks, Paul