A wave has frequency f = 5 Hz and wavelength λ = 60 m in a medium. What is the wave speed c?

A wave has frequency f = 5 Hz and wavelength λ = 60 m in a medium. What is the wave speed c?

• A. 150 m/s
• B. 300 m/s
• C. 600 m/s
• D. 30 m/s

Answer: (B)

The speed of a wave in a medium is found by multiplying its frequency by its wavelength: c = f × λ. With f = 5 Hz (cycles per second) and λ = 60 m (meters per cycle), the speed is c = 5 × 60 = 300 m/s. The units work out since Hz is 1/s, so meters per cycle times cycles per second gives meters per second. This also means that each second, the wave advances 5 cycles and each cycle spans 60 meters, totaling 300 meters per second. If you change either frequency or wavelength, the product fλ adjusts to keep the speed consistent—e.g., a speed of 150 m/s would require a wavelength of 30 m with the same frequency, or a frequency of 2.5 Hz with the same 60 m wavelength.

The speed of a wave in a medium is found by multiplying its frequency by its wavelength: c = f × λ. With f = 5 Hz (cycles per second) and λ = 60 m (meters per cycle), the speed is c = 5 × 60 = 300 m/s. The units work out since Hz is 1/s, so meters per cycle times cycles per second gives meters per second. This also means that each second, the wave advances 5 cycles and each cycle spans 60 meters, totaling 300 meters per second. If you change either frequency or wavelength, the product fλ adjusts to keep the speed consistent—e.g., a speed of 150 m/s would require a wavelength of 30 m with the same frequency, or a frequency of 2.5 Hz with the same 60 m wavelength.