posted by aj .
the pendulum of a grandfather clock is 1.3m long. Determine the length of the arc through which the pendulum moves if it moves through an angle of 15
circumference of the potential whole circle = 2π(1.3)
so , by a simple ratio
arc/2.6π = 15/360
arc = 2.6π(15/360) = (13/120)π or appr .34 m
or 34 cm