fyffe555 is correct that it will take 1/5 of a second.
Your question is what distance it will travel.
s = a t^2/2 (the distance equals 1/2 the acceleration times the square of the time).
Convert the acceleration from inches per minute per second to inches per second per second => 50/6 = 8.33 inches per second per second.
Then the distance = 8.33 * .2 * .2 / 2 = .167 inches
See, I knew that high school physics would come in handy some day. Thanks to "Doc" Rosenberg, my physics teacher -- Dead, but not forgotten.
Ken
Kenneth Lerman
55 Main Street
Newtown, CT 06470