Short Change Resonance of a Damped, driven oscillator

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SUMMARY

When both the spring constant (k) and mass (m) are doubled while keeping the damping constant (b) and driving force magnitude (F0) unchanged, the average power curve P(ω) of a damped, driven oscillator becomes narrower at a higher frequency. This conclusion is derived from the equation of motion m(d²x/dt²) + b(dx/dt) + kx = F0Cos(ωt), where the relationship k/m = ω² indicates that the natural frequency increases with the doubling of k and m. Therefore, the average power curve shifts to reflect these changes in parameters.

PREREQUISITES
  • Understanding of harmonic oscillators and their equations of motion
  • Familiarity with concepts of damping and driven oscillations
  • Knowledge of average power in oscillatory systems
  • Basic calculus for analyzing differential equations
NEXT STEPS
  • Study the effects of varying damping constants on oscillatory motion
  • Learn about the resonance phenomenon in driven oscillators
  • Explore the relationship between mass, spring constant, and natural frequency
  • Investigate the mathematical derivation of average power in oscillatory systems
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Physics students, mechanical engineers, and anyone studying the dynamics of damped and driven oscillators will benefit from this discussion.

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Homework Statement

If both k of the spring and m are doubled while the damping constant b and driving force magnitude F0 are kept unchanged, what happens to the curve, which shows average power P(ω)?

Does the curve:
a) The curve becomes narrower (smaller ω) at the same frequency;
b) The curve becomes narrower at a higher frequency;
c) The curve becomes broader (larger ω) at the same frequency
d) The curve becomes broader at a different frequency;
e) The curve does not change;

The Attempt at a Solution


Equation of motion is:
m\frac{d2x}{dt2}+b\frac{dx}{dt}+kx=FoCos(ωt)

Conceptually, it seems that the amount of power would not necessarily change of k is doubled as is the mass. It also seems that since k/m = ω^2, Δω shouldn't change. Not sure if this is correct.
 
Last edited:
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There's a typographical error in the first term of your equation of motion. After fixing that, divide the equation through by the mass m. Examine the coefficients of each term and determine how the formula for average power would be modified if m and k are doubled.
 

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