The minute hand of a clock revolves at constant angular speed around the face of the clock, completing one revolution every hour. A small piece of modelling clay is attached to the hand with its centre of gravity at a distance 
from the fixed end of the hand, as shown in the figure below.
During a time interval of 
, the centre of gravity of the piece of modelling clay in the figure moves through a total distance of 
. Calculate the magnitude of the centripetal acceleration of the piece of modelling clay.
.
