Why can't we perceive the wavelengths of moving objects like cars?

The reason we cannot perceive the wavelengths of moving objects like cars is that their wavelengths are indeed too small to be observed. In physics, the wavelength of an object is related to its momentum and velocity according to de Broglie's hypothesis, which posits that all moving objects have a wavelength. However, for macroscopic objects like cars, this wavelength is on an incredibly small scale, far below the range of wavelengths that the human eye can detect.

In the case of cars, the de Broglie wavelength is exceedingly tiny due to their large mass and relatively fast speed, making it impossible for us to observe them directly or sense their effects with our eyes. The detection of wavelengths typically occurs in the context of light, sound, or other forms of electromagnetic radiation, where the wavelengths involved are within the range that we can perceive, such as visible light.

Although other choices touch on related concepts—such as the speed of objects or their ability to emit visible light—the fundamental reason lies in the nature of the objects' wavelengths being too small for human perception.