Sound and Echoes Flashcards

Sound Energy

Learning Intentions

  • Understand sound travel and energy transfer.

  • Sound is vibrations transferring energy as waves.

  • No sound in a vacuum: no particles.

  • Sound travels faster in solids due to particle proximity.

Task 1: Sound Energy

  • Sound: energy from vibration, creating waves.

  • No sound in a vacuum: no particles to vibrate.

  • Sound needs a medium (solid, liquid, gas).

Bell in a Bell Jar Experiment

  • Vacuum pump removes air particles.

  • Initially, bell heard.

  • Air removed: bell silent.

  • Air reintroduced: bell audible.

Task 2: Sound Energy & Hearing

  • Loud sound damages hearing (high amplitude).

  • Soft sound: low amplitude.

  • Loud sound exposure: hearing loss (cochlea damage).

  • Inner ear damage permanent; prolonged exposure kills hair cells.

Why Low Volume?

  • Protect hearing (stereocilia).

Task 3: Speed of Sound

  • Fastest in solids, slowest in gases.

  • Solid particles: faster energy transfer.

  • Gas particles: slower energy transfer.

Task 4: Human Hearing

  • Frequency = pitch.

  • Audio Spectrum: 20Hz20Hz to 20kHz20kHz.

  • Hearing decreases with age; most hear ~8,000Hz8,000 Hz.

  • Over 50s: may struggle above 12,000Hz12,000 Hz.

  • Hearing 17,400Hz17,400 Hz: teenager/superhuman.

Setting the Scene: Sound Experiment

  • Question: Highest sound volume location?

  • Independent Variable: Location

  • Dependent Variable: Volume

  • Control: Sound meter, time.

Learning Intention: Echoes

  • Echoes: repeated sounds from reflection.

  • Soft materials muffle by absorbing waves.

  • Audible at 17.2m17.2m (2222 degrees, 340m/s340m/s speed).

Task 2: Animal Echoes

  • Bats/dolphins use echoes to detect prey/obstacles.

  • Ships use sonar to map ocean floor.

Task 3: Echo Calculations

  • Formula: Speed=TotalDistanceTimeSpeed = \frac{Total Distance}{Time}