system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 Why tires appear to be spinning the opposite way

I always notice that when a car is going fast enough, the wheels look like they're spinning backwards instead of forwards, and was wondering if there is an explanation for this.
gpt
Explaining this effect for movies is fairly easy. Its a bit harder for normal vision, but the usual explanation is that the same phenomenon is happening. 

A movie is a series of still pictures played one after the other at a certain rate. Essentially, a movie camera is just a still camera that takes a lot of pictures very fast.

For slow moving objects, when you see the frames played back at speed it looks like the object is moving smoothly. This is because the object does not move very far in each frame, and our eyes and brains can fill in the gaps easily. 

For fast moving objects, this is not always true. If something is moving quickly, it can move quite far in the time between the individual frames of the movie. 

For example, lets say that a wheel was spinning at a rate of one revolution per second, and we took a picture of it once every second. In each picture, the wheel would appear to be in the same place, even though it really made a complete turn. 

If we slow down the wheel a bit but leave the camera the same, things get even more interesting. Now, the wheel will get almost all the way around between each frame. To our brains, it makes a lot more sense that the wheel traveled backwards a small amount than it does that it traveled almost an entire revolution in a small time. Over a lot of frames, our brains decide that the wheel must be spinning backwards.