For 10 points, name these weights suspended on strings that power grandfather clocks.
Francesco Carlini used these devices to determine the density of the Earth. Their periods are nearly 2 pi times the square root of their lengths over gravitational acceleration, but that only holds at small angles for these simple harmonic (*) oscillators. For 10 points, name these weights suspended on strings that power grandfather clocks.
Francesco Carlini used these devices to determine the density of the Earth.
pendulums (prompt on "simple harmonic oscillator" or "S. H. O." before it is read)