A simulation of masses hung from a scale including gravity. Virtual lab tools, including a ruler and a stopwatch can be used to make quantitative measurements. Friction and spring constants can be adjusted, and energy graphed.
Key topics: Hooke's Law, Springs, Conservation of Energy, Measuring Mass and Gravity
For Teaching Tips, see: http://phet.colorado.edu/simulations/sims.php?sim=Masses_and_Springs
