In the Mass-Spring virtual lab at (open the link in a new browser window to prevent your quiz from locking out) http://phet.colorado.edu/new/simulations/sims.php?sim=Masses_and_Springs, set the friction to zero and select planet Earth. Now, if you attach a mass to the spring from its initial equilibrium position, it vibrates forever in simple harmonic motion. Why doesn’t it come to rest after stretching by a distance ‘d’; proportional to the weight of the mass, when the spring’s restoring force cancels out the weight of the mass? How will you measure the equilibrium position? How can you attach the mass to the spring so that it doesn’t oscillate when you let go?