(1) 4 seconds
(2) 4 cm
(3) All Beatles will die - John Lennon, Paul McCartney, George Harrison, and Lingo Star. By eating one another.
The square (A,B,C,D) continues to shrink by 1 cm / second, toward the center. Since the original size of the square is 4 cm (height & width), it takes 4 seconds. The length of each locus is 4 cm (= 4 seconds * (1 cm / second)).
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