In Hollywood movies that have an old-fashioned propeller plane, have you ever noticed that whenever the plane is started, the engine sputters a bit and the propellers start to rotate. Then, when the engine roars to life, the propellers appear to spin in the opposite direction, before gently returning to their original direction of spin.
Has anyone else noticed this?
Without Googling it, can anyone offer a scientifically accurate or imaginarily creative reason for that?
Same question about why tires on other cars sometimes look like they are spinning backwards as you look at them as you roll down the highway.
I used to know the exact science in it, but it has something to do with the frames per second the camera (or your eye on the highway) captures the motion vs the RPM of the spinning object.
Alternatively, it is because objects at rest tend to stay at rest and the wheel or propeller is trying to get back to where it was at rest.
It is a resonance between the rotation of the spinning propeller blades with the frame rate of the video recording device. At just the right ratio of speed a spinning object can appear to be moving in reverse. You get the same effect when you use a strobing light. This is also why CRT’s show lines when recorded on film.
No I did not google any of this.
@ Conall,
Wait. I thought those were just super fancy rims.