In the second photograph the subject is a vertical black object and the background is lit. The object is oscillating from side to side and completed one cycle during the exposure. The sides of the second print are black because the object is stationary briefly there and the gradation is due to its acceleration in Simple Harmonic Motion as the object spends less time obscuring the light as it speeds up. In the middle the object is travelling at its maximum speed and at a density of 1.25 (given above) the exposure time is 1/20 second. The object travels about 1 cm on my screen print size and so is doing 1 cm in 1/20 second so about 20 cm/sec. Chris -----Original Message----- From: owner-photoforum@xxxxxxxxxxxxxxxxxx [mailto:owner-photoforum@xxxxxxxxxxxxxxxxxx] On Behalf Of ADavidhazy Sent: 17 November 2009 22:04 To: List for Photo/Imaging Educators - Professionals - Students Subject: Sample question FYI My students will be taking final exams tomorrow. You can review and ponder about one of the questions (for entertainment value!) at the following URL: http://people.rit.edu/andpph/a-pix/2009-sensi-1.jpg click! andy
