I believe the correct answer from the choices listed above is option B. The soil type that is the richest in organic material would be a dark-colored soil. Decaying matter turns brownish-black which makes this type of soil having a dark color even almost black.
V^2 = 700J/0.5*35kg
V = square root of 40
v = 6.324 m/s
Wavelength is the distance between 2 adjacent points in a wave
we can use the following equation to find the wavelength of a sound wave
wavelength = speed / frequency
frequency is the number of waves passing a point in 1 second
substituting the values in the equation
wavelength = 343 m/s / 686 Hz
wavelength = 0.5 m
wavelength of the wave is 0.5 m
