Harmonic Motion

Oscillator
When investigating harmonic motion we start by identifying the basic cycle. A cycle has a beginning and an end. Between the beginning and end, the cycle has to include all the motion that repeats.

The cycle of the pendulum is defined by where we choose the beginning. If we start the cycle when the pendulum is all the way to the left, the cycle ends when the pendulum has returned all the way to the left. The motion of the pendulum is one cycle after the other with no gaps between cycles.

Music comes from oscillations
Sound is an oscillation of the air. Musical instruments and speakers are oscillators that we design to create sounds. If you gently touch a speaker making sound, you can feel the rapid in-out cycles.

The oscillation travels through the air to where it hits your eardrum. There is harmonic motion at every step, from the original musical instrument to the speaker to the detection of sound in your ear.

Oscillators are used in communications
Almost all modern communication technology relies on fast electronic oscillators. Cellphones use oscillators that make more than 100 million cycles each second. FM radio uses oscillators between 95 million and 107 million cycles per second.

When you tune a radio you are selecting the frequency of the oscillator you want to listen to. Each station sets up an oscillator at a different frequency. Sometimes you can receive two stations at once when you are traveling between two radio towers with nearly the same frequency.

Oscillators are used to measure time
The cycles of many oscillators always repeat in the same amount of time. This makes harmonic motion a good way to keep time. If you have a pendulum that has a cycle one second long, you can count time in seconds by counting cycles of the pendulum.

Grandfather clocks and mechanical watches count cycles of oscillators to keep time. Even today, the world's most accurate clocks keep time by counting cycles of light from a cesium atom oscillator. Modern atomic clocks are accurate to within one second in 1,400,000 years!

Natural cycles involving the Earth
Earth is a part of several oscillating systems. An orbit is a type of cycle because it is repeating motion. The Earth-sun system has an orbital cycle of one year, which means Earth completes one orbit around the sun in a year. The Earth-moon system has a orbital cycle of approximately one month. Earth itself has several different cycles .

The Earth rotates on its axis once a day, creating the 24-hour cycle of day and night. There is also a wobble of the Earth's axis that completes a full cycle every 22,000 years, moving the orientation of the north and south poles around by hundreds of miles. There are cycles in weather, such as El Niño and La Niña oscillations in ocean currents that produce fierce storms every decade or so. Much of our planet's ecology depends on cycles.


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• Simple Motion • Complex Mootion • Features of Motion • Pendulum • Sine Function • Harmonic Systems	Harmonic Systems Oscillator When investigating harmonic motion we start by identifying the basic cycle. A cycle has a beginning and an end. Between the beginning and end, the cycle has to include all the motion that repeats. The cycle of the pendulum is defined by where we choose the beginning. If we start the cycle when the pendulum is all the way to the left, the cycle ends when the pendulum has returned all the way to the left. The motion of the pendulum is one cycle after the other with no gaps between cycles. Music comes from oscillations Sound is an oscillation of the air. Musical instruments and speakers are oscillators that we design to create sounds. If you gently touch a speaker making sound, you can feel the rapid in-out cycles. The oscillation travels through the air to where it hits your eardrum. There is harmonic motion at every step, from the original musical instrument to the speaker to the detection of sound in your ear. Oscillators are used in communications Almost all modern communication technology relies on fast electronic oscillators. Cellphones use oscillators that make more than 100 million cycles each second. FM radio uses oscillators between 95 million and 107 million cycles per second. When you tune a radio you are selecting the frequency of the oscillator you want to listen to. Each station sets up an oscillator at a different frequency. Sometimes you can receive two stations at once when you are traveling between two radio towers with nearly the same frequency. Oscillators are used to measure time The cycles of many oscillators always repeat in the same amount of time. This makes harmonic motion a good way to keep time. If you have a pendulum that has a cycle one second long, you can count time in seconds by counting cycles of the pendulum. Grandfather clocks and mechanical watches count cycles of oscillators to keep time. Even today, the world's most accurate clocks keep time by counting cycles of light from a cesium atom oscillator. Modern atomic clocks are accurate to within one second in 1,400,000 years! Natural cycles involving the Earth Earth is a part of several oscillating systems. An orbit is a type of cycle because it is repeating motion. The Earth-sun system has an orbital cycle of one year, which means Earth completes one orbit around the sun in a year. The Earth-moon system has a orbital cycle of approximately one month. Earth itself has several different cycles . The Earth rotates on its axis once a day, creating the 24-hour cycle of day and night. There is also a wobble of the Earth's axis that completes a full cycle every 22,000 years, moving the orientation of the north and south poles around by hundreds of miles. There are cycles in weather, such as El Niño and La Niña oscillations in ocean currents that produce fierce storms every decade or so. Much of our planet's ecology depends on cycles.

Harmonic Systems