Physics · The potential energy of a spring, conservation of mechanical energy, conservative and non-conservative forces

An ideal spring is hung vertically from the ceiling. When a mass hangs at rest f

An ideal spring is hung vertically from the ceiling. When a \( 2.0 k g \) mass hangs at rest from the spring is extended \( 6.0 \mathrm{cm} \) from its relaxed length. downward external force is now applied to the mass to extend the spring an additional 10cm. While the spring is being extended by the force, the work done by the spring is:

  • A. \( -3.3 J \) \( J \)
  • B. 3.3 .5
  • C. \( -1.67 J \)
  • D. 3.6 \( J \)

Step-by-step solution

The spring constant is determined from the initial equilibrium: k = mg/x = (2.0 kg × 9.8 m/s²) / 0.06 m = 326.67 N/m. The work done by the spring when stretching from x_i = 0.06 m to x_f = 0.16 m is W = -½k(x_f² - x_i²) = -½ × 326.67 × (0.0256 - 0.0036) = -3.59 J ≈ -3.6 J. The magnitude of this work is 3.6 J, which matches option D.
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