A mass of 0.2 kg is attached to the lower end of a massless spring of force-constant 200 N m⁻¹, the upper end of which is fixed to a rigid support. Which of the following statements is/are true?
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Question

A mass of 0.2 kg is attached to the lower end of a massless spring of force-constant 200 N m⁻¹, the upper end of which is fixed to a rigid support. Which of the following statements is/are true?

G1 Physics · Accepted Answer

Equilibrium extension is mg/k=(0.2×10)/200=0.01 m=1 cm, so A is true. Released from unstretched length, it starts 1 cm above equilibrium and reaches 1 cm below equilibrium, i.e. total extension 2 cm, so B is true. ω=√(200/0.2)=√1000≈31.6 rad s⁻¹, f≈5.03 Hz, so C is true. Frequency √(k/m)/(2π) is independent of g, so D is true. Hence A, B, C and D are correct.