Day 25: Doppler Flash

Wednesday, 18 September 2013


This impromptu moment in class while reviewing the Doppler Effect. One of the kids wondered what would you’d hear if something moving really fast was driving toward you. I was ready for this! We watched this clip then ran the numbers for a speed just below the speed of sound.

This led to a few other realizations:

  • the Flash can’t hear anyone around him when he’s running super fast
  • you can’t hear the Flash if he’s speaking while running toward you
  • a radio transmitter as shown in the clip overcomes the problem (“cause radio waves travel so much faster than sound” said one of my kids)

(Side note: I do teach boys but they all sit on the other side of the room. My students are freshmen, so still think the other gender has cooties



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