Physic Labs

Newtonian mechanics

Free fall

Verify that in vacuum every object falls with the same acceleration a=ga=g regardless of mass, and that the distance fallen obeys s=12gt2s=\tfrac12gt^2. Read time and acceleration on the sliders and compare the distance–time plot with the theoretical curve.

Middle school

Equipment

  • Two virtual heavy–light objects released together from the same height
  • Time slider t (0–40 s) and acceleration parameter slider g (0.4–4.0 m/s²)
  • Distance-versus-time plot and Pause button
  • Readout of h=12gt2h=\tfrac12gt^2 with g=9,8 m/s2g=9{,}8\ \mathrm{m/s^2}

Procedure

  1. Release both objects together

    Set the parameter slider near g ≈ 4.0 m/s² and advance the time slider: the heavy and light objects stay at the same height throughout — with drag neglected, fall acceleration does not depend on mass.

  2. Verify the distance fallen

    In figure 2, read the time t on the slider and compare the plotted point with s=12gt2s=\tfrac12gt^2: at t = 2.0 s with g = 9.8 m/s², s ≈ 19.6 m. The curve is a parabola — distance grows as the square of time.

  3. Change gravity and predict

    Drag the parameter slider to its lowest g, then Pause at the same instant t: both objects still fall together but more slowly — the s–t curve flattens in proportion to g. Predict s when g is halved at fixed t, then check on the plot.

Simulation

Experiment history

Galileo Galilei challenged Aristotle's claim that heavier bodies fall faster. In early seventeenth-century inclined-plane experiments he showed that the distance covered grows as the square of time — the legend of dropping weights from the Leaning Tower of Pisa was reported by his pupil Vincenzo Viviani but lacks direct evidence. Isaac Newton placed the result in a system: in the Principia (1687) gravity is proportional to mass while inertia resists motion by exactly that mass, so a=ga=g for every body. In 1971 Apollo 15 astronaut David Scott dropped a hammer and a feather on the Moon — they hit the ground together on camera.

Related physicists

Galileo GalileiIsaac Newton

Related library topics

Free fall