Styrofoam "dancing" question. 1. The problem statement, all variables and given/known data A large peice of plastic is placed on top of a metal cafeteria tray so that there is a small space of air between the bottom of the metal tray and the large plastic piece. In this space are small Styrofoam pieces. When the plastic covering is rubbed with paper, the small Styrofoam pieces "dance" At some point, the Styrofoam pieces stick to the underside of the plastic covering. If I touch the plastic covering right above the Styrofoam piece, the Styrofoam piece falls and may dance some more. 1) Explain why the Styrofoam pieces "dance around" 2) Explain why the Styrofoam pieces fall when I touch the plastic right above them. 2. Relevant equations[/b] No equations needed. 3. The attempt at a solution 1) The plastic has excess electrons which causes the neutral styrofoam to attract....? I'm not sure what causes it to repel from it after though... 2) When I touch the plastic right above them, i am grounded so i discharge the excess electrons. This causes the attraction to stop since the charge of the plastic becomes neutral... I dont know after that.