Hi! I was having some difficulty understanding this concept. If you know how many times per second a wave passes by a point (aka frequency) doesn't that basically say how fast it is? I understand how 2 waves, one with a short wavelength and one with a long wavelength can have the same speed but different frequencies ... but my question is why do they say that the speed will change the wavelength but not the frequency? Because, how can it change the wavelength of an already established wave... by increasing speed, doesn't the frequency automatically increase? Thanks!