I saw this video:
http://www.youtube.com/watch?v...
and wondered what would happen if me and the kids chucked a ball chain off a parking garage roof downtown.
(We were careful not to hit any people. The alley is visible for about 50 feet in any direction. The chain had a shopping bag attached to the end to prevent it whipping about. The jar was attached to the hand rail with a bungee. Yes there is a 4 and 2 year old on the roof of the parking garage. Other than our car, the top two floors of the parking garage were empty. There is a police station on the ground floor so we... took precautions.)
The base of the orange vase is 16.5m (54 feet) above the alley. The camera is an iPhone 4s with a 30 frames per second shutter. The yellow level/ruler is 61cm (24 inches) long and resting on the same base as the vase.
Arch Height:
http://i.imgur.com/Fvz7AQu.jpg...
yellow ruler gives 540 pixels for 0.254m (10 inches.)
Chain top is 1490 pixels above rim of jar
(1490/540)*0.254m = 0.70085m above rim of jar.
Jar is 0.0215m high and almost empty, call it 20cm of free chain in the jar.
So the arch is ~0.9m high.
Speed:
http://i.imgur.com/uSvkWDS.jpg...
Line is: 126 H 772 V pixels
(126*126 + 772*772)^0.5 = 782 pixels
540 pixels is 0.254m (10 inches)
distance is ( 782 / 540 ) * 0.254m = 0.367m
Camera is 30 fps.
Velocity is 0.367m * 30 = 11+ m/s (40kph / 25mph)
(the last bit of chain to fall is not in the vase but is hanging out of the vase, lying on top of the wall nearest the camera with the bag attached to it - perspective means the speed is probably higher.)
Bonus - cleanup in the alley:
http://i.imgur.com/ZCddZ7r.jpg...Originally collected by
fetching...
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