Strange water formation in long exposure

Started Jul 22, 2013 | Questions thread
PeterK Senior Member • Posts: 1,002
Re: Strange water formation in long exposure

Well, here's my 2 cents:

#1: It is definitely one drop of water projected into the air at an angle, forming a classic parabolic projectile motion trajectory.

#2 Something is definitely flashing light on the droplet at even periodic intervals (the distance between the drops caught in the light display the characteristics of projectile motion, where the object travels greater distances near the ground, and smaller distances near the top of its trajectory)

#3 I doubt the full trip took the drop 2 seconds, for this simple reason:

a) from the top of its trajectory to the water's surface would take the droplet the exact same amount of time as from the water's surface to the top - they each take 1/2 the total time in flight (basic physics)

b) If the time to fall from the top of its trajectory is one second, the height would be 5 meters, or about 16 feet. Again, basic physics: all objects in free fall near the surface of the earth fall 5 meters in the first second.

c) as noted previously, it is hard to tell the exact scale, but I don't think that is a 16 ft high arc.

d) The exact time of its trajectory isn't really that relevant though.

#4 The big question is: what is causing the "strobe" effect?

- I don't think anyone has mentioned the second most obvious source of light in the frame, aside from the sun: REFLECTIONS from the WATER.

- Now, what might be causing a periodic reflection from the water?

>> The waterfall hitting some natural barrier at the base of the water that is periodically moved back and forth by the waterfall, or perhaps a pool of water in a rock that is periodically filled and emptied by the waterfall. The possibilities are endless, and I'm sure we could all imagine numerous other physical phenomena that will produce periodic motion at the base of a waterfall - in this case, periodic motion that results in the reflection of the sun's rays into the air where that drop happened to be thrown into the air.

Simple harmonic motion at the base of a waterfall seems a much more probable event than a strobe assist beam lighting that drop at such a large distance - to me, anyway.

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