Constant Acceleration

[gordonjudd]

I was hoping someone might have created a "how-to" video on casting or some similar activity to get me started.

Few,
There are all kinds of Tracker instructional videos on YouTube.

This one showing how to use a moving reference frame attached to one of the point masses is very useful for getting angular velocity plots. You can export data from Tracker to Matlab to smooth the raw digitized data in Matlab using the spaps routine and then import that smoothed data back to Tracker for further analysis.

Gordy

[Few]

Great, thanks. I did do a search or two previously, but probably didn't choose the best search terms because I didn't find what I was looking for. I'll definitely view the video you linked. I haven't used that Matlab spaps function in Matlab, so thanks for that as well. Looks very handy!

Few

[Lou Bruno]

When I read documents that discuss acceleration either constant, smooth, abrupt; they equate acceleration with force. The documents continue to explain what affect that force has on our loops or cast. At times force & acceleration are almost applied as being the same.
Just sharing some thoughts.
Lou

[Graeme H]

Lou,

That’s because F=ma

In English, force is mass being accelerated. Or acceleration is what we get when force is applied to an object.

So, yes, force and acceleration are often used interchangeably here when we discuss stuff.

Cheers, Graeme

[Few]

Yeah, sometimes you can get away with quick and dirty and it pays to keep things simple. As Graeme pointed out, acceleration is proportional to the applied force (they have different units) because \(F=m\cdot a\). But that only holds if the thing being accelerated is a simple rigid mass. Flexible rods with friction (internal damping and air friction), and with an attached line doing crazy things, undermine the simple association. In such cases some of the applied force goes into bending the rod or "working" against friction rather than accelerating the mass. Figuring out how careful you have to be in a given context isn't always obvious at the outset.

Few

[gordonjudd]

I haven't used that Matlab spaps function in Matlab,

Few,
You will also want to use splinetool to home in on a smoothing coefficient value to use in the call to the spaps function. I usually view the first derivative of the data and then vary the soothing value until most of the ripples in the derivative are minimized.
Gordy

[Few]

Ah, good to know. Thanks. I've usually used median filters, or some sort of convolution for other applications, so it'll be fun to learn a new trick. Thanks!
Few

[Lou Bruno]

I'm interested in this topic and it's importance. I've been experimenting with overlining and underlining 5,6, and 7 wt rods; most of the time by 2 line weights. Using the F= m*a equation, I know we're changing the mass component; how would overlining & underlining affect the acceleration?

Lou

[Graeme H]

We still need to reach a given distance, so we still need to provide enough line speed to get there. The acceleration required to reach that line speed should be fairly similar for any given distance.

So with more mass and the same acceleration required, we’ll need to apply more force through the rod.

Cheers, Graeme

[Paul Arden]

I find much higher rates of acceleration downlining as opposed to uplining. Not only can we accelerate faster but we need to with the lighter line to reach the same distance. Certainly I overrod to speed up the shot.

There are other factors at play of course.

Cheers, Paul