Answer:
300 Hz
Explanation:
Something may be wrong on my end because I only see a question labeled 5. Anyways, you can basically just follow the units here.
- Wave speed is in m/s
- Wavelength is in m
- Frequency is in 1/s or s⁻¹, aka Hertz (Hz)
So in order to use the given info to get the correct units...
- Frequency = (Wave speed/Wavelength)
Plugging in or knowns gives us:
Frequency = (120/.4) = 300 Hz
This might be an informal way to think about it technically but it's a good way to do it nonetheless.