How Is Kinetic and Potential Energy Balanced in Harmonic Motion?

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SUMMARY

The discussion focuses on the balance of kinetic and potential energy in harmonic motion, specifically for a mass m attached to a spring with spring constant k. It establishes that the kinetic energy (KE) equals potential energy (PE) at the position x = A/√2. Additionally, when the particle is at x = A/2, the potential energy is calculated to be 0.25 of the total energy, confirming that kinetic energy constitutes 0.75 of the total energy at that position. Energy conservation principles are emphasized throughout the analysis.

PREREQUISITES
  • Understanding of harmonic motion principles
  • Familiarity with kinetic and potential energy equations
  • Knowledge of spring constants and their role in energy calculations
  • Basic algebra for manipulating equations
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  • Study the derivation of energy conservation in harmonic oscillators
  • Explore the implications of spring constant variations on energy distribution
  • Learn about the role of amplitude in determining energy states
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Students of physics, educators teaching mechanics, and engineers involved in systems utilizing harmonic motion will benefit from this discussion.

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(a) Consider a particle of mass m moving along the x-axis under the influence of a spring with spring constant k. The equilibrium point is at x = 0, and the amplitude of the motion is A.

(i) At what point x is the kinetic energy of the particle equal to its potential energy?

For this do i equate KE = PE

.5mv^2 = .5kx^2

*** EDIT ***

I worked this out to be:

.5kx^2 = .25kA^2 (at what value x does the potential energy = half of its maximum)

and worked x out to be A/root(2)

(ii) When the particle reaches point x = A/2, what fraction of its total energy is kinetic energy, and what fraction is potential energy?

For this i don't know how to relate x = A/2 to kinetic energy

*** EDIT ***

if the max energy of the system is .5kA^2 then at x = A/2 the PE is .5k(A/2)^2 which is one quarter of the total PE so the rest is KE?

so does this mean that .25 is PE and .75 is KE?

This has become quite frustrating so any ideas would be great!
 
Last edited:
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Don't panic! You are correct! :approve:

Energy is conserved, so at any point: KE + PE = .5kA^2
 

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