Simple harmonic motion (SHM): A particle executes simple harmonic motion. At which position in its path does it attain the maximum speed, and why?

Difficulty: Easy

Correct Answer: through the mean position

Explanation:


Introduction / Context:
In simple harmonic motion (SHM), a particle oscillates about a mean (equilibrium) position under a restoring force proportional to displacement. Understanding where speed is maximum is fundamental to vibration theory and helps connect energy concepts with kinematics in oscillatory systems.


Given Data / Assumptions:

  • Displacement x varies sinusoidally about the mean position.
  • Amplitude A is the maximum displacement on either side.
  • Angular frequency is ω (constant).
  • No damping or external forcing; pure SHM.


Concept / Approach:
For SHM, velocity v is given by v = ω * sqrt(A^2 - x^2). Alternatively, v = dx/dt when x = A sin(ωt + φ). Maximum speed occurs when the square root term is largest, i.e., when x = 0. Energy view: at the mean position, potential energy (stored in the spring or restoring element) is minimum and kinetic energy is maximum, so speed peaks there.


Step-by-Step Solution:

Position dependence: v(x) = ω * sqrt(A^2 - x^2).Maximize v ⇒ maximize (A^2 - x^2) ⇒ x = 0.At x = 0 (mean position), v_max = ωA.


Verification / Alternative check:
At extremes x = ±A, v = 0, matching the observation that the particle turns around at the endpoints. Between extreme and mean, v increases; it is largest exactly at the centre.


Why Other Options Are Wrong:

  • Extreme point: speed is zero there (turning points).
  • Half amplitude: speed is non-zero but not maximum.
  • “None of these” contradicts the SHM velocity relation.


Common Pitfalls:
Confusing maximum displacement with maximum speed; in SHM they do not coincide. Also, mixing angular frequency ω with linear frequency f without conversion.


Final Answer:
through the mean position

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