A good temporary weight you can use until you reach a professional is a small plastic water bottle. Tie the bottle to the pendulum and keep adding water to add weight until the clock keeps the correct time.

Similar to what was observed for the mass on a spring, the position of the pendulum bob (measured along the arc relative to its rest position) is a function of the sine of the time.

The left/right part of a circle is a cosine function; that’s the definition of cosine. So, since the two pendulums keep the same time, the planar one shakes back and forth as a cosine function, too. (Your question asked for why it’s a sine function, but these are essentially the same, and equally-valid solutions.)

The pendulum is passive. The weight of the pendulum is not linked to the clockworks; wheels, pinions, pivots, bushings, etc. Its entire weight is suspended from a suspension spring, and at worst if it is too heavy the clock will stop.

For example, if the bob weighs 2 kilograms (kg), the calculation is 3.36 m/s^2 x 2 kg = 6.72. This is the force pushing the pendulum bob, measured in newtons.

Foucault’s pendulum is an easy experiment demonstrating the Earth’s rotation. At any other point on Earth, however, the point at which the pendulum is attached cannot be considered a “fixed point,” because that point also moves as the Earth rotates. The plane in which the pendulum swings is similarly in motion.

Calculate the period of oscillations according to the formula above: T = 2π√(L/g) = 2π * √(2/9.80665) = 2.837 s . Find the frequency as the reciprocal of the period: f = 1/T = 0.352 Hz . You can also let this simple pendulum calculator perform all calculations for you!

The to and fro or back and forth motion of a body repeatedly about a fixed point (mean position) is called oscillation and one complete cycle of repititive to and fro motion from one point to another and then again back to that point is called one complete oscillation.