Periodic Motion: Explaining Resolving into Oscillatory Components

In summary, the textbook states that any periodic motion can be broken down into simpler oscillatory components through the use of a Fourier Series. This method involves decomposing the motion into a sum of basic periodic functions, such as sines and cosines. This can also be applied to the periodic motion of the Earth, by deriving an equation for the forces acting on it and using Fourier to decompose it into a sum of sines and cosines. Kepler's laws describe the periodic motion of the planets around the Sun.
  • #1
PrincePhoenix
Gold Member
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According to our textbook "..every periodic motion, however complicated it may be, can always be resolved into simple oscillatory components." Can someone explain this? How can the periodic motion of Earth be resolved into oscillatory components?
 
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  • #2
Hey PrincePhoenix,

I believe what your textbook is referring to is the idea of a Fourier Series. The mathematician and physicist derived a method with which it is possible to decompose any periodic function to a sum of basic periodic functions, namely sines and cosines. By manipulating the amplitudes of several (often infinite) sines and cosines, it is possible to construct the desired function.

To learn more about the actual computation of the series, just search the web for Fourier series and harmonic analysis.

http://mathworld.wolfram.com/FourierSeries.htmlAs far as the periodic motion of the Earth goes, if you can come up with a clean equation for the forces acting on it, it is possible to derive the periodicity of the Earth's motion. Using Fourier, I assume you would be able to decompose this into a form of an infinite sum of sines and cosines.

Hope this helps a bit!
 
  • #3
Thanks.
 
  • #4
Simple periodic motion is usually described as being like the motion of a pendulum in a gravitational field, or Hookes Law for a spring
http://en.wikipedia.org/wiki/Pendulum
http://en.wikipedia.org/wiki/Hooke's_law
where the restoring force is (nearly) proportional to the displacement from the center.
http://en.wikipedia.org/wiki/Hooke's_law
But the planetary motion around the Sun is also periodic, and is described by Kepler's laws.
http://en.wikipedia.org/wiki/Kepler's_laws_of_planetary_motion

Bob S
 

Related to Periodic Motion: Explaining Resolving into Oscillatory Components

1. What is periodic motion?

Periodic motion refers to any type of motion that repeats itself at regular intervals. This can be seen in a variety of natural phenomena, such as the changing of seasons, the swinging of a pendulum, or the vibrations of a guitar string.

2. What is the difference between simple harmonic motion and periodic motion?

Simple harmonic motion is a type of periodic motion where the restoring force is directly proportional to the displacement from the equilibrium position. In other words, the motion follows a sinusoidal pattern. However, not all periodic motion follows this specific pattern, making simple harmonic motion just one type of periodic motion.

3. How is periodic motion related to oscillation?

Oscillation refers to the back and forth motion of an object around an equilibrium position. Periodic motion is a type of oscillation, as the object repeats its motion at regular intervals. However, not all oscillatory motion is necessarily periodic, as it may not have a specific pattern or frequency.

4. What are the factors that affect the period of a periodic motion?

The period of a periodic motion is affected by several factors, including the mass and stiffness of the object, as well as the strength of the restoring force. In addition, the amplitude and frequency of the motion also play a role in determining the period.

5. How can we resolve a periodic motion into oscillatory components?

To resolve a periodic motion into oscillatory components, we can use Fourier analysis. This involves breaking down the motion into a series of simple harmonic motions with different frequencies and amplitudes. This allows us to better understand the different components that make up the overall periodic motion.

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