Why can pendulums be used for time keeping?

Answer 1

The period of oscillation of the pendulum is

T=2 pi sqrt(L/g)

T- Period
pi – 3.14159...
L – Length from suspension point to the center of mass
G – acceleration due to gravity

This way the time period is fixed by constants like length and acceleration due to gravity.

Answer 2

Think of one swing of the pendulum as one unit of time. You can measure anything using this, only you would call it something like one pendulum. Good for comparing or measuring time differences. Example: I can hold my breath for 21 pendulum swings. This would be relative time.

You could calibrate it to actual time but that gets harder. Let's say a swing of a pendulum takes 1.6 seconds. Count the pendulum swings. Multiply that number by 1.6 and you get the seconds of time it takes for that event to happen. This would be actual time.

So you can measure relative time or if calibrated, actual time.

Answer 3

Well, pendula (the plural of pendulum) move in simple harmonic motion which is periodic and anything that is periodic can be used to measure time.

Answer 4

Since gravity moves the weight back and forth evenly (look into physics if you really want to know all of that science), it's very rhythmic and precise.