Optical illusion causes whirling blades to appear almost stationary

The wagon-wheel effect, here caused by videotaping a high-speed veggie-chopping machine, makes it look like the blades are only slowly moving, even as cucumber slices fly out at a scary-fast speed. This stroboscopic phenomenon is also commonly seen on footage of cars and airplane propellers, captured at odd intervals by the camera's shutter.

Luckily, looking at this machine in real life would allow one to see how fast it's spinning. 

Still, I wouldn't feel comfortable standing anywhere near this machine. The fate of the cucumber tells me all I need to know.