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P H O T O G R A P H Y C O N T E S T Sponsored by A.J. Hirsch |
Chris
North Toronto Collegiate Institutel
Second Place
2007 OAPT 4U Photo Contest
The Fountain of Life
An eyewash station is a vital part of every physics classroom, and a perfect demonstration of projectile motion. As the water is ejected with constant velocity, it follows a parabolic path as the force of gravity pulls it back towards the Earth. Both photos were taken of the same eyewash fountain within a semi-dark physics lab. Other than shutter speed and lighting, all conditions were kept constant. The first photo was taken with a shutter speed of 1/100 of a second with flash while the second photo was taken with a shutter speed of 15 seconds with no extra lighting. In comparison, the second photo better demonstrates the parabolic path. The first photo, with a 1/100 second exposure time, gives the impression that water flows in gushes. This is caused by the cohesion of polar water molecules. The second photo has an exposure time that is 1500 times longer than the first photo. This results in a blurred image that shows the average flow of the water, which negates the effects of cohesion and presents an overall parabolic path.