Meter Based on Seconds Pendulum
This section introduces an old definition of 'meter' which uses a seconds pendulum. A 'meter' is the length of a seconds pendulum, which swings a full cycle in 2 seconds in small angles.
The French National Assembly also accepted another definition of 'meter' to be
"the length of a pendulum with a half-period of one second" in year 1790.
This definition is based on the factor that a small angle pendulum with a half-period of one second
will have a length of about one meter,
as illustrated in the picture below:
Since "meter" is defined more accurately now with the speed of light,
the accurate length of a seconds pendulum at the sea level is 0.994 meter.
With this knowledge, you can actually create your own 1 meter string as a measuring tape.
- Get a long thing string and tie a small rock at one end.
- Hold the other end of the string and lift the rock in the air.
- Push the rock to let it swing freely in small angles.
- Using a stop watch to count the number of seconds it takes to swing 10 full cycles.
One full cycle is a forward swing and a backward swing.
- Adjust the holing position of the string until you count 20 seconds for 10 full swing cycles.
- Stop the swing. The distance between the holding position and the center of the rock is 1 meter.
- Cut extra parts of the string and you get a 1-meter string.
Table of Contents
About This Book
►Introduction of Space
What Is Space
What Is Distance
Meter Based on Earth's Meridian
►Meter Based on Seconds Pendulum
Meter Prefixes and Other Units
List of Various Distances and Lengths
Introduction of Frame of Reference
Introduction of Time
Introduction of Speed
Newton's Laws of Motion
Introduction of Special Relativity
Time Dilation in Special Relativity
Length Contraction in Special Relativity
The Relativity of Simultaneity
Introduction of Spacetime
Minkowski Spacetime and Diagrams
Introduction of Hamiltonian
Introduction of Lagrangian
Introduction of Generalized Coordinates
Phase Space and Phase Portrait
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