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Idealisations in the simple harmonic oscillator

Hello,

Could someone walk me through some idealisations made in the theory behind the simple harmonic oscillator? I know friction is ignored, but could you explain some others too please? :confused:

Thanks

Reply 1

uberteknik

Original post by bluemohito

Hello,

Could someone walk me through some idealisations made in the theory behind the simple harmonic oscillator? I know friction is ignored, but could you explain some others too please? :confused:

Thanks

SHM refers to anything with a sinusoidal type periodic function describing the motion.

Therefore, anything that alters the amplitude of the function is a deviation from the ideal and is dependent on the application.

i.e. energy losses caused by friction, air resistance, heat transfer, sound, em radiation etc. etc.

Reply 2

andromeda24

properties of an object undergoing SHM (in easy terms):

- the object oscillates about a mid-point/centre position.

- acceleration of an object is proportional to the displacement of that object.

- the acceleration acts in the opposite direction to the gain in amplitude/displacement ( acceleration proportional to -displacement)

Hope this helps :smile:

Reply 3

-G-a-v-

For a mass-spring system, we assume the spring is massless and elastic.

Reply 4

bluemohito

Original post by uberteknik

Yes, thank you for that.

Then, if SHO misses out things like friction, air resistance ... then why do scientists rely on it?

Reply 5

uberteknik

Original post by bluemohito

Yes, thank you for that.

Then, if SHO misses out things like friction, air resistance ... then why do scientists rely on it?

SHM is the 'ideal' case oscillator. It's only valid for text book explanations describing perfect oscillations and to describe the oscillation frequency and it's relationship to physical properties in as simple way as possible. It's used to understand how the oscillations are sustained, that frequency is independent of amplitude.

In practice all oscillators are damped since they experience energy losses as previously described. The simple oscillator equations must therefore be modified to account for these losses.
In this case, the amplitude of oscillation can only be maintained by an equal but opposite driving force which exactly compensates the damping.