-- The wavelength and the amplitude were described in my answer to your previous question.
-- A "compression" is a place where the wave is <em>compressed</em>. It's the darker section of the wave in the picture, where the wavelength is temporarily shorter, so several waves are all bunched up (compressed) in a small time.
-- A "rarefaction" is exactly the opposite of a "compression". It's a place where the wave gets more "<em>rare</em>" ... the wavelength temporarily gets longer, so that several waves get stretched out, and there are fewer of them in some period of time. The arrow in the picture points to a rarefaction.
Divide the distance traveled by the time it took:
(100 m) / (4.2 s) ≈ 23.8 m/s
Answer:
(a) 1555.6m^3
(b) 17284m^3
Explanation:
Density of helium=0.18kg/m^3, density of hot-air balloon=0.18-(0.1×0.18)=0.18-0.018=0.162kg/m^3, total mass of people, basket and balloon=280kg
(a) volume = mass/density=280/0.18=1555.6m^3
(b) volume = mass/density = 280/0.162= 1728.4m^3
