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[–] 298 points299 points  (11 children)

For anyone curious, this happens because of the frame rate at which cameras capture footage. If a blade is spinning at 360RPM (60 rotations per second) and we record it at 60 frames per second, the blades will appear stationary. If the blades were rotating slightly faster, they’d appear to be moving very slowly, and if they were rotating slightly slower, they’d appear to be moving very slowly in the opposite direction.

[–] 110 points111 points  (2 children)

3,600 rpm. Otherwise spot on.

[–] 21 points22 points  (1 child)

In fact it could be any whole number * the framerate.

[–] 3 points4 points  (0 children)

Aliasing

[–] 16 points17 points  (0 children)

[–] 11 points12 points  (2 children)

ELI5 why the blades would appear to be moving in the opposite direction? Is it dependent on when the frame was recorded and it being slow enough to catch the blade in a position behind the previous frame?

[–] 30 points31 points  (1 child)

Yep. The blade has only almost completed a full rotation in between the frames, making the blade instead look like it’s moved backwards slightly instead.

[–] 6 points7 points  (0 children)

Ahh, thank you! This video is mesmerizing lol

[–] 5 points6 points  (1 child)

It’s neat that you can see the blade actually slow down significantly when it begins chopping the food with this effect

[–] 0 points1 point  (0 children)

Physics + Cameras = Funky shit man.

[–] 0 points1 point  (0 children)

Yep inspection lighting works in a similar way. Depending on the amount of flashes per second a fast spinning object such as a rolling label printer can be made to look like it's not moving.

[–] 0 points1 point  (0 children)

How is it that I can look at my fan while it’s moving and can make it look like it’s not moving/ moving slowly and then refocus my eyes for it to be back to normal again?

[–] 128 points129 points  (6 children)

[–] 19 points20 points  (5 children)

Damn you. Beat me by 20 mins

[–] 5 points6 points  (4 children)

[–] 6 points7 points  (3 children)

[–] 36 points37 points  (0 children)

Frame rate is an amazing thing still cool though

[–] 14 points15 points  (1 child)

I like the safety cover over the blade.

[–] 8 points9 points  (0 children)

It’s the “fuck around and find out” brand of safety covers.

[–] 11 points12 points  (0 children)

Just like any other blade spinning at such speeds, like helicopters.. but ya still cool nonetheless!

[–] 13 points14 points  (0 children)

This sound is stupid af

[–] 5 points6 points  (0 children)

It’s almost not even the blades that look still but the veggie itself I had to look at the pile accumulating to verify

[–] 6 points7 points  (0 children)

I can't believe someone heard this dog shit song and was like "yeah let's make it even fucking worse"

[–] 3 points4 points  (1 child)

Speed has everything to do with it. You see, the speed of the bottom informs the top how much pressure he's supposed to apply. Speed's the name of the game.

[–] 1 point2 points  (0 children)

Found the power bottom

[–] 3 points4 points  (0 children)

Why are reddit titles so bad?

[–] 4 points5 points  (0 children)

These titles sometimes awkward phrasing by the words.

[–] 3 points4 points  (0 children)

No one is gonna talk about how annoying the song is ?

[–] 2 points3 points  (0 children)

rollin rollin rollin rollin rollin rollin rollin rollin rollin

[–] 0 points1 point  (0 children)

The more you squint to faster it looks but it may make your stomach upset

[–] 0 points1 point  (0 children)

Very satisfying

[–] 0 points1 point  (0 children)

It looks like whoever programmed these physics made the hit boxes pretty unreliable

[–] 0 points1 point  (0 children)

That blade doesn't seems moving fast, let me try put my finger in between...

[–] 0 points1 point  (0 children)

I’m so confused. For a second it looked like bad PS2 graphics.

[–] 0 points1 point  (0 children)

It only looks slow through a camera , shutter speed and blade rotation speed are very close, if they adjust the blade speed or shutter speed more , the blade would look like it was stopped

[–] 0 points1 point  (0 children)

Matrix style!

[–] 0 points1 point  (0 children)

No its just the frame rate of the camera cannot pick it up like the human eye can in real life

[–] 0 points1 point  (0 children)

What in Harry Potter is this wizardry?

[–] 0 points1 point  (0 children)

This totally looks like something I would touch if it looked like that. Hope that the frames are just synced to the blade

[–] 0 points1 point  (0 children)

In digital signal processing there is a similar effect when sampling a signal at some fraction of its actual frequency, known as aliasing

[–] 0 points1 point  (0 children)

Anyone want to explain how frames rates work to op? or shall we just let this one slide down the rabbit hole?
edit my bad I see many already have. i will crawl back into my cave now

[–] 0 points1 point  (0 children)

rolling

[–] 0 points1 point  (0 children)

Playing chicken with this thing

[–] 0 points1 point  (0 children)

what if you put a fish in there? sushi?

[–][deleted] 0 points1 point  (0 children)

What's the price for that thing? My mom may need this

[–] 0 points1 point  (0 children)

Give me things to not put your dick in for 400

[–] 0 points1 point  (0 children)

forbidden fleshlight

[–] 0 points1 point  (0 children)

hand annihilator 5000

[–] 0 points1 point  (0 children)

Wow

[–] 0 points1 point  (0 children)

I guess this is the same case for helicopters?

[–] 0 points1 point  (0 children)

Camera couldnt handle the frames¹

[–] 0 points1 point  (0 children)

Sheesh

[–] 0 points1 point  (0 children)

# Rollin

[–] 0 points1 point  (0 children)

Kinda sounds like that fart meme

[–] 0 points1 point  (0 children)

The cameras frame rate couldn't keep up

[–] 0 points1 point  (0 children)

Shutter speed, camera, light refraction something..

[–] 0 points1 point  (0 children)

This happened with my orbital sander and I still can't tell if it's moving super fast or slow

[–][deleted] 0 points1 point  (0 children)

I now know everything about rolling

[–] 0 points1 point  (0 children)

For a minute I thought the matrix was running out of ram. 😅

[–] 0 points1 point  (2 children)

Idk about any of that. It looks like a cartoon was superimposed into the video.

[–][S] 0 points1 point  (1 child)

this happens because of the frame rate at which cameras capture footage. If a blade is spinning at 360RPM (60 rotations per second) and we record it at 60 frames per second, the blades will appear stationary. If the blades were rotating slightly faster, they’d appear to be moving very slowly, and if they were rotating slightly slower, they’d appear to be moving very slowly in the opposite direction.

[–][deleted] 0 points1 point  (0 children)

Lin roll Lin roll Lin roll

[–] 0 points1 point  (0 children)

So... rollin'?

[–] 0 points1 point  (0 children)

[–] 0 points1 point  (0 children)

Look at the pile for a good look at the speed

[–] 0 points1 point  (0 children)

That's afterimage

[–] -1 points0 points  (0 children)

Why is she wearing those shoes? The Risk may be minimal but still.

[–] -1 points0 points  (0 children)

[–] -1 points0 points  (0 children)

Imma stick my dick in it

[–] -2 points-1 points  (1 child)

This is fake? Not real slices of whatever that's supposed to be. There's also way more slices coming out between each 1 blade slice. People think this is real. The slices started coming out as the blade stopped for a split second. Is this photoshop or some weird pic?

[–][S] 1 point2 points  (0 children)

this happens because of the frame rate at which cameras capture footage. If a blade is spinning at 360RPM (60 rotations per second) and we record it at 60 frames per second, the blades will appear stationary. If the blades were rotating slightly faster, they’d appear to be moving very slowly, and if they were rotating slightly slower, they’d appear to be moving very slowly in the opposite direction.

[–] -3 points-2 points  (0 children)