-In the Figure Above,some Wavefronts Are Emitted by a Source

question 21

Multiple Choice

-In the figure above,some wavefronts are emitted by a source of sound S.This picture can help us to understand

• A)why the siren on a police car changes its pitch as it races past us.
• B)why a sound grows quieter as we move away from the source.
• C)how sonar works.
• D)the phenomenon of beats.
• E)why it is that our hearing is best near 3000 Hz.

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Definitions:

Demand Curve

A graph showing the relationship between the price of a good and the quantity of the good that consumers are willing to buy.

Midpoint Formula

A method used in geometry to find the midpoint or the center point between two points on a line segment.

Absolute Value

The non-negative value of a number regardless of its sign.

Elasticity

a measure of how much the quantity demanded or supplied of a good responds to a change in one of its determinants, such as price.