other

• fahrenheit -> celsius

  T k = T C + 273
• Spd of light in vacuum

  3.0 x 10^8 m/s
• sound wave spd


  330-350 m/s
• diameter milky way

  100 000 light year
• light year


  9.5 x 10^5 m
• Hubble constant estimate


  2.2 x 10^-8 per sec
• ultrasound frequency


  higher 20 kHz
• F (centripedal force)

  = mv^2 / r
• range of audible frequency

  20 Hz to 20 kHz