Vibrations Flashcards
how is sound produced?
a vibrating element which is immersed in a natural medium
what is a vibration?
the back and forth motion which repeats itsself periodically
-it requires a restoring force which increases displacement
what are the 5 key properties of a vibrating system?
displacement (m) amplitude (m) period (t) frequency (Hz) Phase
displacement
distance of object from its ⇌ position (m)
amplitude
maximum displacement from its ⇌ in (m)
period (t)
time for one complete vibration in seconds
frequency
the no. complete vibrations/second measured in Hz
f=1/T
T=1/f
Phase
a measure of the degree to which the waves are in step
measure of the position of the vibrating object in its motion (used to compare the motion of 2 vibrarting objects
out of phase by t/4 =90 degrees
t =360 degrees
different degrees of damping?
depends on the medium in which system vibrates
lightly damped –>spring in air
heavily damped –> spring in honey
what is damping?
the steady decrease of a vibrating system due to energy losses int he system (as a result of friction)
what is critical damping?
when a displaced body returns to ⇌ without passing through it in the shortest time possible
(human ear is critically damped)
what is forced vibration?
when a system is kept vibrating by the application of an external force at a different frequency to its own natural frequency
what is resonance?
when an object is kept vibrating by applied periodic force at a frequency which is the same as the object’s natural frequency
at resonance what happens to the amplitude?
it increases to the maximum value and there is a maximum transfer of energy
therefore the maximum transfer of energy (from one system to another) can only be performed at resonant frequency
what is a wave?
produced when a vibrating object passes its energy to a neighbouring object
–> energy is transmitted from one location to another
