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Frequency of oscillation of a ball?

  1. Jul 3, 2014 #1
    1. The problem statement, all variables and given/known data

    Hi,

    For one of my physics projects i need the natural frequency, or frequency of oscillation of a ball. I don't even know where to start. I've got a short article of an experiment similar to mine where they also use this natural frequency. So if my story is unclear, which im sure it is, you can take a look and see if that makes it any clearer.

    http://www.fas.harvard.edu/~scidemos/OscillationsWaves/SaddleShape/SaddleShape.html

    Thanks in advance.

    2. Relevant equations

    None so far

    3. The attempt at a solution

    Also, none so far, as i don't understand it really, sorry.
     
    Last edited: Jul 3, 2014
  2. jcsd
  3. Jul 3, 2014 #2
    I found out a text which may help you to understand what natural frequency is:

    "As has been previously mentioned in this unit, a sound wave is created as a result of a vibrating object. The vibrating object is the source of the disturbance that moves through the medium. The vibrating object that creates the disturbance could be the vocal cords of a person, the vibrating string and soundboard of a guitar or violin, the vibrating tines of a tuning fork, or the vibrating diaphragm of a radio speaker. Any object that vibrates will create a sound. The sound could be musical or it could be noisy; but regardless of its quality, the sound wave is created by a vibrating object.

    Nearly all objects, when hit or struck or plucked or strummed or somehow disturbed, will vibrate. If you drop a meter stick or pencil on the floor, it will begin to vibrate. If you pluck a guitar string, it will begin to vibrate. If you blow over the top of a pop bottle, the air inside will vibrate. When each of these objects vibrates, they tend to vibrate at a particular frequency or a set of frequencies. The frequency or frequencies at which an object tends to vibrate with when hit, struck, plucked, strummed or somehow disturbed is known as the natural frequency of the object. If the amplitudes of the vibrations are large enough and if natural frequency is within the human frequency range, then the vibrating object will produce sound waves that are audible.

    All objects have a natural frequency or set of frequencies at which they vibrate. The quality or timbre of the sound produced by a vibrating object is dependent upon the natural frequencies of the sound waves produced by the objects. Some objects tend to vibrate at a single frequency and they are often said to produce a pure tone. A flute tends to vibrate at a single frequency, producing a very pure tone. Other objects vibrate and produce more complex waves with a set of frequencies that have a whole number mathematical relationship between them; these are said to produce a rich sound. A tuba tends to vibrate at a set of frequencies that are mathematically related by whole number ratios; it produces a rich tone. Still other objects will vibrate at a set of multiple frequencies that have no simple mathematical relationship between them. These objects are not musical at all and the sounds that they create could be described as noise. When a meter stick or pencil is dropped on the floor, it vibrates with a number of frequencies, producing a complex sound wave that is clanky and noisy."

    Also I found a formula:
    Frequency (omega) is equal to the speed of vibration divided by the wavelength (lambda).
    ω=v/λ
     
  4. Jul 3, 2014 #3
    The short article you linked is quite interesting but seems unrelated to your question. Can you clarify?
     
  5. Jul 3, 2014 #4
    I think he's problem is about this part:
    The interval of rotational speeds leading to stability is centered about 147RPM (2.45 Hz) which is indeed twice the ball's natural frequency.
     
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