Measuring Wave Speed Flashcards
All 6 cards in this deck
State the equation linking wave speed, distance and time, with units.
wave speed (m/s) = distance (m) ÷ time (s), i.e.
What are the steps to measure the speed of sound in air over a measured distance?
e.g. two students 100 m apart, one firing a starting pistol- Measure the distance between them: 100 m
- Time from seeing the flash/smoke to hearing the bang
- Use to get the speed of sound
Why do stopwatch timings for sound travelling 100 m vary so much between students?
Reaction time is large compared with the travel time, and is different for each student.
Give one improvement to measuring the speed of sound in air with a stopwatch, and its effect.
Use a much longer distance, or use an electronic timer (microphones/data logger) — this reduces the impact of reaction time and gives a more measurable time.
Why should a student repeat the timing and take a mean when measuring the speed of ripples across a ripple tank?
To reduce the effect of random errors in the timing, giving a more reliable value for the speed.
To measure the wavelength of sound, two microphones start side by side in front of a speaker and one is moved away until their oscilloscope traces line up again. What does the distance between the microphones then equal?
One wavelength of the sound wave.