Clever question. Pretty simple, but we never think of the details
quite in this order.
-- The 'seconds' hand on the watch goes all the way around in 1 minute.
The tip of the hand moves in a circle.
-- 15 seconds is 1/4 of a complete 1-minute revolution.
So the 2 cm is 1/4 of the way around the circle that the tip makes.
-- The full circumference of the circle is 8cm.
-- The length of the second hand is the radius of the circle.
2 pi radius = circumference
2 pi radius = 8 cm
Divide each side
by 2 pi : radius = 8cm / 2 pi = 1.27 cm
(choice - A)
