Links for 2010-04-15

  • “Let’s motivate our question a little bit. I’ve wondered about this question since I saw star wars. Though I’m no firearms expert, the recoil in guns must come from conservation of momentum principles. Momentum is conserved in a system. The gun starts with zero momentum. We fire, give the bullet momentum, and so to keep the system at zero momentum, the gun must gain equal and opposite momentum. That is, the gun will move backwards.

    All of that was for conventional guns. Light carries momentum, so if we fire a pulse of light, we expect our laser gun to recoil. So yes, they do have recoil. Satisfied, dear readers? Neither am I. The question we really mean to ask is, does a laser gun have noticeable recoil?”

  • “The Boy has his mother’s spatial sense and a touch of my nerdiness, so he was all over the science fair.

    He loves bridges and earthquakes, so this year he decided to do a project that combined them. His project involved building bridges of two different designs — ‘beam’ and ‘suspension’ — and subjecting both of them to simulated earthquakes while supporting weight. The idea was to see whether one design would hold up better than the other.

    It takes a village to do a science fair project.”

  • “Shortly after I posted a video of the recently released Fermilab Rap, Funky49 himself found the post and left a comment. Also known as Steve Rush, Funky49 was kind enough to agree to an interview about his rap career, science outreach as a hobby, nerdcore, and School House Rock. “
  • Deriving the world’s most famous equation using a flashlight in a space ship.