Answer:
4) The Doppler effect is the frequency change that occurs in a wave by the relative movement of the emitter and the observer
5) Sound originates from a repetitive movement of air molecules
6) The principle of stable superposition that if the medium complies with the elastic regime, the waves traveling in it can be added
Explanation:
4) The Doppler effect is the frequency change that occurs in a wave by the relative movement of the emitter and the observer. In the specific case of the fixed observer, each wave that is emitted travels at a constant speed, but as the emitter approaches the next wave lLa in less time, so the wave maxima are closer to each other
v = λ’ f’
λ‘=λ -Δλ = λ - vs / f
f’= v / λ’ = v / (λ - vs / f) = v / (v / f - vs / f)
f ‘= f v / (v-vs)
5) Sound originates from a repetitive movement of air molecules, this movement creates a longitudinal wave, which we call sound. It is characterized by the air volume module and its density
6) The principle of stable superposition that if the medium complies with the elastic regime, the waves traveling in it can be added
y total = y₁ + y₂
Let's see as an example two waves of the same amplitude that travel in the same direction, if this wave the maximums coincide they add up obtaining that the maximums are twice the amplitude
If the wave goes in the most directive but the maximum of one coincides with the minimum in the other, the sum gives zero,
The wave travels in the opposite direction, in this case the resulting wave in constant in time and we call it resonance
