Sound. If a tree falls in the forest and there is nobody around does it make a sound?
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Transcript of Sound. If a tree falls in the forest and there is nobody around does it make a sound?
Sound
Sound
If a tree falls in the forest and there is nobody around does it make a sound?
Sound
•Disturbance (energy source)
•Medium (wave travels through)
•Air•Water•Steel
Sound in (Medium) Air
Compression waves travel through air
Sound wave are called Longitudinal Waves
Sound in (Medium) Air
Sound can not travel in a vacuum
Speed of Sound
The speed of sound in dry air at 0oC is about 330 meters per second ( 330m/s )
770 miles per hour mph
Speed of Sound
Water vapors in the air increase the speed of sound slightly
Speed of Sound
Increase in temperature also increases the speed of sound
For each 0oC, the speed of sound in air increases by 0.06m/s
Example:
At normal room temperature of about 200C sound travels at about 340m/s
Loudness
Loudness is sound intensity.
The greater the disturbance (intensity) the greater the sound wave
Loudness is measured in units of Decibel (dB)
Forced Vibration
The transfer of vibration from the primary medium to secondary medium, increasing amplitude
Natural Frequency
When an object composed of an elastic material is disturbed, it vibrates at its own special set of frequency, which together forms a special sound.
We speak of an object’s natural frequency, which depends on factors such as the elasticity and shape of the object
Resonance
When the frequency of a forced vibration on an object matches theObject’s natural frequency, a dramatic increase in amplitude occurs
This phenomenon is called resonance.
Resonance means to re-sound or sound again.