Attach a mass to a spring, release it, and verify Hooke's law F = –kx. Measure the period, visualise phase space, and add damping.
Drag a Circle body onto the canvas. In the Forces panel, add a Spring force and attach the other end to a fixed anchor point directly above the mass. Set spring constant k = 50 N/m, natural length = 2 m, and mass m = 1 kg.
Displace the mass 0.5 m from equilibrium and pause the simulation. Check the force readout in the body panel — it should read F = 50 × 0.5 = 25 N directed toward the anchor. Try three different displacements and confirm F ∝ x.
Release the mass from 1 m displacement. Enable the graph panel (G key) and plot position-y vs time. Measure the time between two peaks — this is the period T. Compare to the formula T = 2π√(m/k). For k=50, m=1, expect T ≈ 0.89 s.
Switch the graph panel to position-y vs velocity-y (phase space). An undamped oscillator traces a perfect ellipse. Note how the ellipse's size corresponds to the total energy of the system — more displacement means a larger ellipse.
In the body's force list, add a Linear Drag force with coefficient b = 2 N·s/m. Re-run the simulation and observe the graph: the ellipse spirals inward toward the origin as the system loses energy. This is underdamping. Increase b to 20 to reach critical damping — the mass returns to equilibrium without oscillating.
Discussion
Questions, corrections, and insights welcome.