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⚛️ Physics  ·  Oscillations  ·  NEET & JEE

A block on a spring (k = 200 N/m) is given an initial displacement of 5 cm and initial velocity of 1 m/s. The amplitude of oscillation (mass = 2 kg) is:

Answer: 0.1 m.

  • A 0.1 m
  • B 0.05 m
  • C 0.15 m
  • D 0.2 m

Correct answer: A. 0.1 m

Explanation: Total E = (1/2)kx_0² + (1/2)mv_0² = (1/2)(200)(0.05)² + (1/2)(2)(1)² = 0.25 + 1 = 1.25 J. E = (1/2)kA² → A = √(2E/k) = √(2.5/200) = √(0.0125) ≈ 0.112 m.

Displacement, Velocity, Acceleration in SHMx(t)v(t)a(t)v leads x by 90°; a is exactly out of phase with x (a = −ω²x)

In SHM, displacement and velocity are 90° out of phase (v is maximum when x=0, and zero when x is extreme), while acceleration is always exactly opposite in sign to displacement, consistent with a = −ω²x.

Concept context

Simple harmonic motion, spring-mass, pendulum, energy in SHM, and resonance.

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