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. the matter that a longitudinal wave travels through is called the medium. in a longitudinal wave, the wave and the particles of matter move in parallel directions. if a longitudinal waves frequency decreases and its speed stays the same, its wavelength decreases.

Explanation:

Step1: Analyze the relationship between frequency and energy

The energy of a wave is related to its frequency. The formula for the energy of a wave (in general, applicable to various types of waves including longitudinal waves in a qualitative sense) is \(E = hf\) (where \(h\) is Planck's constant and \(f\) is frequency). As frequency \(f\) increases, energy \(E\) increases. So, the statement "If a longitudinal wave's frequency increases, the energy carried by the wave increases" is True.

Step2: Define the medium

The medium is the matter through which a wave travels. For a longitudinal wave (like sound waves in air or the wave in the spring toy), the matter (air molecules or the coils of the spring) through which it travels is called the medium. So, the statement "The matter that a longitudinal wave travels through is called the medium" is True.

Step3: Examine particle - wave direction in longitudinal waves

In a longitudinal wave, the particles of the medium vibrate parallel to the direction of wave propagation. For example, in a sound wave (a longitudinal wave), air molecules move back - and - forth in the same direction that the sound wave is moving. So, the statement "In a longitudinal wave, the wave and the particles of matter move in parallel directions" is True.

Step4: Analyze the relationship between frequency, speed, and wavelength

The wave speed formula is \(v=\lambda f\) (where \(v\) is speed, \(\lambda\) is wavelength, and \(f\) is frequency). If \(v\) is constant (\(v = \lambda f\Rightarrow\lambda=\frac{v}{f}\)), when \(f\) decreases, \(\lambda\) increases (since \(\lambda\) and \(f\) are inversely proportional when \(v\) is constant). So, the statement "If a longitudinal wave's frequency decreases and its speed stays the same, its wavelength decreases" is False.

Answer:

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