1. why does the atomic model keep changing? people discovered that atoms are made up of even smaller particles. then the models change because of how we think atoms are composed

Go on  answers.com it has the answer, also jiskha.com has a lot of test answers for connexus 

Firstly, the water in the dams hold gravitational potential energy as they are above ground level. the gravitational potential energy is then transferred to kinetic energy as it falls, spinning the turbinethe turbine then spins the generator, which is a large magnet surrounded by metal coils. by doing this, the generator generates electricity. in this action, the energy transfer taken place is kinetic to electric energy