Unit Vectors and Their Derivatives

For this video I wanted to show spherical coordinate unit vector derivatives, and decided that it needed background with polar coordinates first, so at 4 + min it is longer than usual.
My website, Ko-fi, and so on can be found here:

[zephyrwatch]

You have no idea how thankful I am for this video. I unironically spent 3 hours trying to understand this concept, and apply it to finding the acceleration vector in spherical coords the way my textbook presented it. Then I watch this amazing 4 1/2 min long video and everything made sense. You are a saint.

[jackcrane]

Super informative and very easy to understand thank you! :)