Physics

Physics

Problem

Two identical particles execute simple harmonic motion with the same angular frequency but different amplitudes A1=0.10 mA_{1}=0.10\,\text{m} and A2A_{2}. At a displacement of 0.05 m0.05\,\text{m} from their respective mean positions, the ratio of their kinetic energies is 1:31:3 (first to second). What is the value of A2A_{2}? a) 0.25 m0.25\,\text{m} b) 0.16 m0.16\,\text{m} c) 0.19 m0.19\,\text{m} d) 0.17 m0.17\,\text{m}
Intuitive explanation

The key insight is that kinetic energy in SHM depends on both the amplitude and the current displacement through energy conservation. At any position xx, the kinetic energy is KE=12mω2(A2−x2)KE = \frac{1}{2}m\omega^2(A^2 - x^2), which comes from the total mechanical energy minus potential energy. Since both particles have the same mass and frequency but different amplitudes, you can set up a ratio of their kinetic energies at the same displacement and solve for the unknown amplitude.

Intuitive explanation

The key insight is that kinetic energy in SHM depends on both the amplitude and the current displacement through energy conservation. At any position xx, the kinetic energy is KE=12mω2(A2−x2)KE = \frac{1}{2}m\omega^2(A^2 - x^2), which comes from the total mechanical energy minus potential energy. Since both particles have the same mass and frequency but different amplitudes, you can set up a ratio of their kinetic energies at the same displacement and solve for the unknown amplitude.

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