1. A mechanical wave is a disturbance that travels through a medium, transferring energy from one place to another without permanently displacing the medium itself.
2. Sound usually travels through air, but it can also travel through liquids and solids. It requires a medium because it relies on the vibration of particles to propagate.
3. No, sound cannot travel through empty space (a vacuum) because there are no particles to vibrate and transmit the energy.
4. In a transverse wave, particles move perpendicular to the direction of wave travel (e.g., shaking a rope up and down). In a longitudinal wave, particles move parallel to the direction of wave travel (e.g., compressions and rarefactions in a slinky).
5. Sam should stretch out a slinky horizontally between two fixed points or have a partner hold one end. He should then push and pull one end of the slinky back and forth along its length. This will create regions of compression (particles close together) and rarefaction (particles spread apart) that travel along the slinky, demonstrating a longitudinal wave.
6. A high-pitched sound has a higher frequency (more waves per second), which means the source vibrates more rapidly. A low-pitched sound has a lower frequency (fewer waves per second), meaning the source vibrates more slowly. Pitch is directly related to frequency.
7. Loudness is determined by amplitude—the greater the amplitude of a sound wave, the louder the sound. Amplitude reflects the energy carried by the wave; larger amplitudes mean more energy and thus greater loudness, measured in decibels.
8. Lisa’s statement is incorrect. While it's true that higher frequency corresponds to higher pitch, humans do not hear all frequencies equally well. Human hearing typically ranges from 20 Hz to about 20,000 Hz, and sensitivity varies across this range. Additionally, loudness (amplitude) and pitch (frequency) are separate properties—she might perceive a high-frequency sound as “louder” if it’s also high in amplitude, but frequency alone does not determine loudness.
Parent Tip: Review the logic above to help your child master the concept of sound waves worksheet.
