Wheels.

[Mexican18]

Why do wagon wheels appear to be going backwards? I was told years ago but have forgotten. I think it has something to do with strobes.

[spathiphyllum]

It's the wagon wheel affect.

It's because each spoke of a wheel is in a slightly different position to the one it was when it was first saw.

[fiction-factory]

[fiction-factory]

I also included a scientific explanation link but that didn't appear

[Mexican18]

Thanks both of you.

[fiction-factory]

https://www.geek.com/news/geek-answers-why-do-wheels-seem-to-spin-backwards-at-high-speeds-1565327/

[Old_Geezer]

It's because each frame of the film shows the spokes in a particular position. If in the following frame the spoke has, say, moved 90% forward towards to the place where the spoke in front of it had been, your brain interprets that as an apparent 10% movement backwards instead.

The wheel can appear to be going either clockwise or anticlockwise depending on the rotational speed of it, compared to the speed the film frames are being taken/viewed.

[spathiphyllum]

our eyes work like video cameras when looking at wheels spin. We see frame by frame, unless we follow a SINGLE spoke then we see the wheel go round very fast. These frames are slightly out of tempo which causes the wagon wheel affect. If they are in tempo, the affect isn't present. It's usually slightly under tempo rather than over giving the appearance that the wheel is going backwards, but in reality it's actually going forwards twice as fast.

This is very hard to articulate and i'm glad FF provided a video because well.. there go you :)

[Mexican18]

Thanks Geezer.F.F's link explained it perfectly.

[Mexican18]

Thanks again Spath.

[spathiphyllum]

I thought the video was very well executed

[johnk]

They've gone backwards with the amount of chocolate on them!!

[Peter Pedant]

to do with the frame speeds of the film , telly innit?

we were told that it didnt occur in real life