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# M4.4.2

Has a basic understanding of the concept of velocity and how it is measured.

### What the Doppler Effect Tells Us About Distant Stars and Planets

Police officers, air traffic controllers, and astronomers all use the Doppler Effect to determine the speed of an object as it approaches or recedes from their radars or telescopes. The frequency (or pitch, for sound) of waves coming from a moving object is changed an amount directly proportional to the speed of approach or recession. The effect of the change, to raise or lower the frequency, specifically indicates that the source is approaching or receding, respectively.

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### Launch Speed

This example is a simple application showing how Newton's laws of motions are used on aircraft carriers. As with any practical application of physics, it is important to be aware of your units of measure, and the meanings of all the terms in the equations.

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