Determine the wavelength propagating at a speed of 2 m / s, in which 10 oscillations occur in 20 s.

To begin with, we determine the period of wave oscillations from the expression:
T = t / n, where n is the number of oscillations, t is the time during which the body made these oscillations.
The wavelength is equal to the distance that the waves propagate in a time equal to the oscillation period of the source.
λ = v * T, where v is the propagation velocity, T is the wave period.
Let’s substitute in this expression the formula with which you can determine the period:
λ = v * T = v * t / n
Substituting numerical values and determine the wavelength:
λ = v * t / n = 2 * 20/10 = 4 m.
Answer: the wavelength is 4 m.