Answer:
21.81 ft
Step-by-step explanation:
For an arc of measure α and radius r, the arc length is ...
s = r·α . . . . . . where α is in radians
Then the linear speed is ...
s' = r·α'
Here the rate of change of arc angle is (π/3)/(17.3) rad/s, so the radius can be found to be ...
r = s'/α/ = (1.32 ft/s)/((π/3)/17.3 rad/s) = 1.32·3·17.3/π ft
r ≈ 21.81 ft
The length of the pendulum is about 21.81 feet.
