200 likes | 303 Vues
Saturday Sept 12th: Spring tides and sneaker waves . Functions. relation. function. linear function. Sine and cosine functions, oscillation period = 2 π. 0. 2 π. The unit circle. The addition rule. Wave superposition. 1 wave:. f = frequency. T =period= 1/f. h o = amplitude.
E N D
Functions relation function linear function
Wave superposition 1 wave: f = frequency T=period=1/f ho = amplitude 2 waves: same amplitude (for simplicity) but different frequency
Wave superposition 1 wave: Addition rule: f = frequency T=period=1/f ho = amplitude 2 waves:
The Seventh Wave A product of sine and cosine with different frequencies
Beats wave envelope = mean frequency fm = beat frequency fb
WAVES ENVELOPE
Beats = mean frequency fm = beat frequency fb
Swell and sneaker waveson theOregon Coast Log carried by sneaker wave April 2007, Cannon Beach OR
Sum of 9-second swell and 11-second swell Mean period = 9.9s Beat period = 49.5s
Lunar tides 2 bulges2 high tides per day Moon orbits Earth every 30 days Tidal frequency = 2/24hrs-1/30days =1/12.4hrs Tidal period = 12.4 hrs
Solar tides Earth orbits Sun every 365 days Tidal frequency = 2/24hrs-1/365days =1/12.0hrs Tidal period = 12.0 hrs
Spring tide Constructive interference Tidal range is HIGH OR
Neap tide Destructive interference Tidal range is LOW
Tides at Newport, Sept 12-20 2009 Sat 12 Sun 13 Mon 14 Tue 15 Wed16 Thu 17 Fri 18 Sat 19 Sun 20 Spring tides