Pendulums:

• Florida gravity (30° latitude) = 32.1302
  


• 4Pi² / 32.1302 = 1.2287
  


• 1 / 1.2287 = .8138
  


• A 2-second period (tick-tock) pendulum in Florida has a length of 39.065" (3.255').
  


• These formulas actually apply to a pendulum with an infinitely small swing, but they give a reasonable approximation if the angle isn't too large!



• Find Period when given Length
  Time = SQRT ((4Pi² * Feet) / Gravity)
  Time = SQRT (Feet * 1.2287)
  Time = SQRT (Feet / .8138)
  2 seconds = SQRT (3.255 * 1.2287)
  2 seconds = SQRT (3.255 / .8138)



• Find Length when given Period
  Length (feet) = Time² * (Gravity/4Pi²)
  Length (feet) = Time² * .8138
  3.255 feet = 2² * .8138