Question

eli creates longitudinal waves in the spring toy.
select the true statements about longitudinal waves.
if a longitudinal waves frequency increases, the energy carried by the wave increases.
if a longitudinal waves frequency decreases and its speed stays the same, its wavelength decreases.
in a longitudinal wave, the wave and the particles of matter move in parallel directions.
the matter that a longitudinal wave travels through is called the medium.

Explanation:

1. Wave energy is directly proportional to frequency; higher frequency means higher energy, so this statement is true.
2. Using the wave speed formula $v = f\lambda$, if $v$ is constant and $f$ decreases, $\lambda$ must increase, so this statement is false.
3. By definition, longitudinal waves have particles oscillating parallel to the wave's direction of travel, so this statement is true.
4. The matter that a wave propagates through is universally defined as the medium, so this statement is true.

Answer:

• Correct statements:

1. If a longitudinal wave's frequency increases, the energy carried by the wave increases.
2. In a longitudinal wave, the wave and the particles of matter move in parallel directions.
3. The matter that a longitudinal wave travels through is called the medium.

• Incorrect statement:

1. If a longitudinal wave's frequency decreases and its speed stays the same, its wavelength decreases.