How a Geek Sees the World

(Original source unknown)

Hi, I'm @sicilian, and I recently discovered Steemit while watching Jeff Berwick's YouTube videos.  I'm not very good at talking about myself, so I thought I'd write a post giving some insight into the mind of a geek.

While looking for cute dog pictures to cheer up a friend, I stumbled on the one above.  I knew that the motion blur of the dog's tail was caused by the fairly long exposure time of what was likely a cheap digital camera.  Then I thought about what was causing the gaps in that blur, giving it the peacock feather look.  This is likely due to "light hum" - variation in output of the room lighting due to alternating current utility power.

"The city lights of Prince George, British Columbia viewed in a motion blurred exposure. The AC blinking causes the lines to be dotted rather than continuous.  (By RadRafe (Own work) [Public domain], via Wikimedia Commons)" - Wikipedia

The AC frequency is likely either 50 or 60 cycles per second, so we can get a rough estimate of how fast the dog's tail is moving.  The tail looks to be about one foot long.  Counting the gaps between the "peacock feathers", there appears to be about ten gaps in 180 degrees of angle swept out by the tail.  The tip of the tail moves a distance of about pi feet over this semicircle.  Assuming 60 cycles per second, the time this takes is ten 60ths of a second, or 1/6th second.  Multiplying pi feet by 6 gives the distance the tip of the tail moves in a second: almost 19 feet.  Finally we need to break out the calculator.  Multiplying 19 feet per second by 3600 seconds per hour, and then dividing by 5280 feet per mile, we get about 13 miles per hour as the approximate speed of the tip of the dog's tail.  That's almost 6 meters per second or close to 21 km/h.  OK, that's not as impressive as a bumblebee or hummingbird, but still pretty fast.

Yes, I'm the guy who sees a cute picture of a dog and wants to do math! I hope you enjoyed this post, and am looking forward to posting more soon.  My main interests in addition to math, science, and cute animals include trading, economics, cryptocurrencies, freedom, chess, poker, food, and many more.