Second time’s the charm
Last Saturday was the vernal equinox (equal parts daylight and night), and so I wanted to talk about the tilt of the planet and how it effects our seasons. That leads us into talking about how the planets are in elliptical orbits and we wrap up the night with some history of astronomy. We also answer the Office Hours Problem of the week (#OHPOW) from the last two weeks and we answer a viewer question about electric plugs.
OHPOW from March 19th- 0:02:34 - Deals with Free body diagrams and Newton's Laws of motion.
OHPOW from March 26th - 0:11:48 - Deals with permutations and combinations.
Viewer question "Why do electric plugs have those little holes?" - 0:18:28 - Thanks for the question Divya! We discuss why some electric plugs have those little holes in the prongs while some don't. If you are interested in learning more about electric plugs and sockets from all over the world, check out the digital plug and socket museum: http://www.plugsocketmuseum.nl/index.html.
The tilt of the planet - 0:29:14 - We go though how the tilt of the planet creates the different seasons.
The elliptical motion of the planets - 0:37:00 - We go through the evidence that supports an elliptical versus circular orbit. I show you how to make an ellipse using two push pins and a bit of yarn.
Centripetal force demostration - 0:48:00 - To reconstruct this demo, you need a wiffle ball (or you can use a ping pong ball and tape the yarn to it), yarn or twine, a straw, and some weights (washers are ideal). Holding the straw try spinning the ball at different speeds and see how it affects the radius of rotation. Check out my Patreon for the full activity.
Back to the calculations - 0:53: 20 - Using Newton's law of universal gravitation and the definition of centripetal force we work through a circular approximation for the orbit of the Earth and Mercury. We also work through unit conversions and linear to rotational quantity conversions. We also work through how long it takes for sunlight to reach us.
Brief history of Astronomy - 1:44:29 - We walk through the history of astronomy starting with Aristotle and a geocentric universe to Issac Newton and the law of universal gravitation. (sorry for my overhead camera blocking most of the slide)
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