Thermometer there's others you can use but i know that's one of them
Well, I think the answer would be 4 meters because the speed is in meters per second and the frequency is 5 waves every 2 seconds.
Wavelength = Speed/Frequency
I think the frequency is 2.5 waves a second but that's not something I'm 100% sure about.
I hope this helps though.
Nutrients, moisture and aeration and structure
