Spring and string pendulum (oscillations)

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SUMMARY

The discussion revolves around the dynamics of a pendulum influenced by a spring, specifically focusing on the equation of motion for small angles (α << 1). The equation derived is α'' + (k/m)⋅α = 0, leading to the angular frequency ω = √(3k/m) and the equilibrium angle αR = 2⋅B. Participants clarify the initial conditions and the role of gravity, ultimately arriving at the corrected equation of motion α'' + ((g/L) + (k/m))⋅α = 0, which incorporates gravitational effects. The conversation highlights the importance of accurately interpreting initial conditions and forces acting on the pendulum.

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  • Understanding of simple harmonic motion (SHM)
  • Familiarity with pendulum dynamics and torque
  • Knowledge of spring mechanics and Hooke's Law
  • Basic calculus for solving differential equations
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  • Explore the effects of damping in oscillatory systems
  • Learn about the small angle approximation in pendulum motion
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Students and educators in physics, mechanical engineers, and anyone interested in the dynamics of oscillatory systems, particularly those involving springs and pendulums.

  • #31
JulienB said:
@haruspex I imagine so since it was a problem at a real exam a couple of years ago. Well I read the problem again and nothing's stated about t=0 until question c) and it is unfortunately for α = 0 then.
Yes, my remark about t=0 was only in relation to part c.
For part b, the only other suggestion I have is that it should say to find αR in terms of m, L, k and x0.
 
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  • #32
Also, if I assume that α(0) = αR, I think it implies that B = 0.
 
  • #33
haruspex said:
Yes, my remark about t=0 was only in relation to part c.
For part b, the only other suggestion I have is that it should say to find αR in terms of m, L, k and x0.

Yes and that could be easily done with the force equation right? Well, thank you for your help in any case! Was my reasoning in part c) coherent?Julien
 
  • #34
JulienB said:
Yes and that could be easily done with the force equation right? Well, thank you for your help in any case! Was my reasoning in part c) coherent?Julien
In the equation you posted for α'(0) you had a sign wrong, but that must have been a mistake in typing the post since the answer you got is right.
 
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