Question

directions: you will be moving around the room to different stations with your lab groups. at each station, follow the directions and then answer the questions. some stations might be more time consuming and require you to return to them at later stations that are not as time consuming to finish. you may also learn things at the other stations that you want to incorporate later. it is totally ok to return to a previous station as long as you have finished with the current station you are on. station 1: steel spheres have one group member hold a piece of paper in the air. another group member should hold one sphere in each hand and bang them together with the paper in between the spheres. 1. what happens to the paper? 2. why do you think this happened? 3. what type of energy transformation took place during this station? 4. relate what happened at this station to conservation of energy. how does this back up the claim that energy is neither created nor destroyed?

Explanation:

1. When steel spheres are banged together with paper in between, the force exerted by the spheres on the paper causes holes to form. This is because the spheres apply a concentrated impact on the paper.
2. The reason holes form is due to the transfer of mechanical energy from the moving spheres to the paper. The kinetic energy of the spheres (from being moved and banged) is used to break the paper fibers at the point of contact.
3. The energy transformation here is from kinetic energy (of the moving spheres) to mechanical energy (doing work on the paper to create holes).
4. In terms of conservation of energy: The energy used to create the holes (mechanical work on the paper) comes from the kinetic energy of the spheres. The total energy before (kinetic energy of spheres) and after (some kinetic energy lost as it's converted to mechanical work on paper, heat due to friction, sound energy from the bang etc.) is conserved. Energy isn't created - it was already present as kinetic energy in the moving spheres, and it isn't destroyed - it just changes forms (to mechanical work, heat, sound etc.).

Answer:

1. The paper gets holes.
2. Because the kinetic energy of the moving spheres is used to break the paper fibers (mechanical work on the paper).
3. Kinetic energy (of spheres) is transformed into mechanical energy (to make holes in paper).
4. The energy to make holes (mechanical work) comes from the spheres' kinetic energy. Total energy (kinetic + other forms like heat, sound after) is conserved. Energy just changes forms, not created or destroyed.