Feedback on video I created on (Galilean) Relative Velocity?

I've decided to try my hand at creating youtube videos and I'd like to know what fellow PF members think. This is a community whose opinions I value.

The video can basically be divided into 6 slides (about 18 minutes long in total)

1) Definition of relative velocity (verbally)
2) Definition of relative velocity (graphically and mathematically)
3) - 4) A simple linear example to cultivate intuition/convince viewers of the validity of the formula
5) Back to the generalization from slide 2) with an explanation of when two objects are not traveling in a straight line (relative to some frame S)
6) Invariance of relative velocity between two objects is independent of frame of reference from which the velocities are given

I'd like feedback on

1) The accuracy of the physics in general and specifically slide 6, is what I'm saying right?

2) Quality and smoothness of animations; Rendering it in AVI via matlab produced good quality, however I feel like a lot of it was lost when converting it to H.264 mp4 via "Handbrake" in order to open it in Adobe Premiere. If this is a problem is there a nice work around?

3) Timing of animations with audio, is the pace reasonable?

4) Anything else you could think of that would make this video better

I'd welcome any criticisms (and compliments)/suggestions from PF members. I'd be very grateful to anyone who took the time to help me.

Cheers

I suspect one of the reasons you are not getting any feedback is also one of the things you should be considering when making instructive videos on YouTube: It is too long. So long in fact that nobody (including myself) bothered to watch it to provide feedback.

When making this type of videos you should be aiming around the 3-5 minute mark. You will not keep an audience longer than that in general. They are on the internet, it is fast paced, there are other videos in their feed.

Try to distill down the absolute essentials and, if necessary, split the material into several more or less self-contained bits.

Orodruin said:

I suspect one of the reasons you are not getting any feedback is also one of the things you should be considering when making instructive videos on YouTube: It is too long. So long in fact that nobody (including myself) bothered to watch it to provide feedback.

When making this type of videos you should be aiming around the 3-5 minute mark. You will not keep an audience longer than that in general. They are on the internet, it is fast paced, there are other videos in their feed.

Try to distill down the absolute essentials and, if necessary, split the material into several more or less self-contained bits.

I appreciate your feedback!

I will try that! Along with making "youtube shorts" as teasers.

I tried being as comprehensive/thorough as possible but going forward I'm going to split the video into more short self-contained parts.

Again, I really appreciate you taking the time to provide feedback!

I did watch the whole thing, and had a nagging feeling that those who need it don't have the knowledge to follow the argument. And those who can understand what's presented, don't need it any more because they already know it.

There's more detailed things I noticed while watching (twice). In no particular order:

i.e. is not spoken language (at least not for most non-native english speakers)

the lettering is difficult to read. I watch on a 24 inch screen and found some text awkward
,
Times modern roman is not a good font on a screen

'We are first going to look at this from person A's perspective' is directly followed by an animation (of what ?, well, A's position (while moving !?) in the system S). I am afraid that amounts to wrong-footing a large fraction of the audience...

You manage to confuse me with the notation ##\vec D_{B|A}## for what to me has always been ##\vec r_{AB}##
(but later on ##\vec v_{B|C}-\vec v_{A|C} = \vec v_{B|A}## looks (plausible...)

'D stands for distance or position or displacement ' ? whichever you like ? I sure don't like 'distance'...

##\vec D_{B|A}## is shorthand for B relative to A --- we are still in frame S, and have no idea which way A has to look in his/her own frame to see B since we don't know anything about A's frame of reference (right ?)

I don't think the terms 'mythical stationary frame S', 'god-like frame' should be necessary in the argument. And so often...

Do those who know what a time derivative is, stilll pick up anything from this video ?

Coming back to the animations: after a few of them I realize that what's animated is only the drawing of a vector ... !?! And it seems to go slower and slower. Same for the slowly popping up of texts

'From A's perspective'(you sure it isn't from S's perspective?) is then repeated in exactly the same tempo to a second 'important result' for ##\vec v_{A|B}##. It could have been shortened somewhat ...

'Remember that every person thinks they are the center of the universe' -- Do we really need that ?

'Not travelling along the same line' is not what I would call non-linear

ah, finally, after more than half a minute:

At the closing scene you need another frame, C. Is it moving ?

Sorry if this is all negative. Invert it and it becomes positive

I am sure this has been a lot of work; hats off !

##\ ##

First of all thank you for your response! I think the overall takeaway is that I got careless with nomenclature, labels, and illustrations assuming that people knew what I was talking about.....which if that were the case it would defeat the purpose of making a video.

BvU said:

I did watch the whole thing, and had a nagging feeling that those who need it don't have the knowledge to follow the argument. And those who can understand what's presented, don't need it any more because they already know it.

I can see that. I need to remember it is not a review for me but an exposure (possibly a first exposure) to someone else. Which makes all your points below even more informative.

BvU said:

i.e. is not spoken language (at least not for most non-native english speakers)

the lettering is difficult to read. I watch on a 24 inch screen and found some text awkward

,

Times modern roman is not a good font on a screen

I assumed most of my potential viewers would have english as their mother tongue, perhaps a bad assumption, and even worse a hindrance to getting more views.

Does the lettering problem still persist when choosing to watch it in 1080p?

I rendered it in Uncompressed AVI, then converted it to H.264 mp4, because Adobe Premiere couldn't open AVI. Perhaps I should have rendered it in H.264 mp4 to begin with?

BvU said:

'We are first going to look at this from person A's perspective' is directly followed by an animation (of what ?, well, A's position (while moving !?) in the system S). I am afraid that amounts to wrong-footing a large fraction of the audience...

I should have clearly defined a frame S coordinate system, and an A, and a B one as well. More work, you're right it would be more accurate.

BvU said:

'D stands for distance or position or displacement ' ? whichever you like ? I sure don't like 'distance'..

Yeah I don't have an excuse for that

BvU said:

D→B|A is shorthand for B relative to A --- we are still in frame S, and have no idea which way A has to look in his/her own frame to see B since we don't know anything about A's frame of reference (right ?)

Yup same problem, need to clearly define a coordinate system for S,A, and B.

BvU said:

Do those who know what a time derivative is, stilll pick up anything from this video ?

I would like to think so but probably not?

BvU said:

'From A's perspective'(you sure it isn't from S's perspective?) is then repeated in exactly the same tempo to a second 'important result' for v→A|B. It could have been shortened somewhat ...

Again got lazy with labeling things and assumed the person knew what I meant. (Bad Assumption)

BvU said:

'Not travelling along the same line' is not what I would call non-linear

Fair, completely fair, should have said 'constant' or something like that.

BvU said:

ah, finally, after more than half a minute:

Lazy editing, should have zoomed in further on my video timeline and cropped it right.

BvU said:

At the closing scene you need another frame, C. Is it moving ?

I need to think about how I would display that graphically while still retaining information from other "slides"

BvU said:

I am sure this has been a lot of work; hats off !

It has and I'm still learning (naturally), this sort of feedback is tremendously helpful!!

BvU said:

Sorry if this is all negative. Invert it and it becomes positive

That's the hope!! I'm pretty sure next video(s) will be as much work if not more work (Circular motion, uniform, and non-uniform, minimum speed to loop a roller coaster)(definitely gonna break this one up per the suggestions of this thread). But now I have an idea about how to direct it!

I really appreciate you taking the time to watch the 19 minute video (twice).