If a movie camera takes a picture of a spinning spoked wheel

Solution

The sampling theorem dictates that the sampling rate must be twice the sampled signal in order to be able to recover the original data. It can be seen in the AM modulation, to be able to recover the original data (baseband message) in the receptor of the communication system, the carrier frequency (that would act as the sampler function) must have a frequency that has to be at least twice the baseband message highest frequency. If not, the data would be distorted and the message won\'t be properly recovered.

The same happens in this case. If the images produced by the camera show the wheel turning at a rate different from reality it is because the images were taken at a rate lower than twice the wheel turning rate. Therefore, the camera won\'t be able to recover the original data.