Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <Redmo-at-aol-dot-com> for the 1 cm case: L = 17.8 cm = .178 m not .018 m v = 6986 cm/s = 70 m/s not 7 m /s F = .0024Kg * (70m/s)^2/.089m = 132.1 Newtons = 29.7 lbs not 1.48 lbs ! Russ