Calculating the Speed of Waves

Key Concepts

• Amplitude: Maximum displacement from the undisturbed position.
• Wavelength: Distance between two equivalent points on consecutive waves.
• Frequency: Number of waves passing a point per second, measured in Hertz (Hz).
• Wave Speed: Speed at which the wave travels through a medium and how quickly energy is transferred.

Wave Speed Equation

• Formula: Wave speed (m/s) = Frequency (Hz) × Wavelength (m)
• Important: This equation is not given in exams and needs to be memorized.

Sample Problems

Problem 1

• Given: Frequency = 165 Hz, Wavelength = 2 m
• Solution: Wave speed = 165 Hz × 2 m = 330 m/s

Problem 2

• Given: Frequency = 10,000 Hz, Wavelength = 2 cm
• Conversion: 2 cm = 0.02 m
• Solution: Wave speed = 10,000 Hz × 0.02 m = 200 m/s

Problem 3

• Given: Wave Speed = 500 m/s, Frequency = 200 Hz
• Solution: Wavelength = Wave Speed / Frequency = 500 m/s ÷ 200 Hz = 2.5 m

Measuring Speed of Sound in Air

• Experiment Setup:
  • Two people 500 meters apart: Person A (cymbals), Person B (timer)
• Method:
  • Person B starts timer when cymbals are clashed, stops when sound is heard.
  • Calculate speed using: Distance / Time

Experiment Challenges

• Reaction Time: Human reaction time may cause errors.
  • Mitigation: Use multiple observers, discard anomalies, compute mean.
• Short Time Intervals: Quick intervals make timing difficult.
  • Mitigation: Increase distance between observers to elongate time span.

Additional Resources

• Study Material: Access further questions on wave equations and sound wave speed measurement in the review workbook.