Final answer:
The amplitude of a wave is half the height from peak to trough, so a 2 m crest above still water has an amplitude of 1 m. A seagull bobbing every 2 seconds between 3 m apart crests experiences a wave velocity of 1.5 m/s. A boat hit by a 2 m high wave peak will change elevation by 2 m.
Step-by-step explanation:
The question provided is related to the physics of waves, specifically their propagation, amplitude, frequency, and wavelength. When discussing a wave crest measuring 2 m above the still water mark, the amplitude of the wave is actually 1 m, as the amplitude corresponds to the maximum displacement from the equilibrium (still water level) to the peak of the wave, which would be half of the peak-to-trough height.
Therefore, if a wave's crest is 2 m above the still water mark, and assuming the trough is the same distance below, the amplitude is 1 m.
Similarly, for a seagull bobbing up and down on the water's surface, if it does so once every two seconds and the distance between two crests of the water wave is 3 m, the velocity of the wave would be 1.5 m/s (wavelength divided by the period: 3 m / 2 s = 1.5 m/s).
Regarding a boat that bobs up and down due to wave action, if the height of the wave is 2 m, the boat's height will change by 2 m when hit by the peak of the wave, considering the change from the equilibrium position to the peak.