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Mr. Manning was not here today, so we had a substitute teacher. We watched a movie in class on work and energy. We also had to fill out a worksheet while watching the movie. It was 12 questions long and we went over all the questions at the end of the period. Here are the answers: 1. Energy is always conserved (all the time). 2. Conservation of Energy means the total amount of energy in all the universe is constant (never changes). 3. We calculate the amount of work done when lifting an object by Work = force x height which is the same as Work = mgh. 4. The potential energy of an object is calculated as: U = mgh (it is equal to the work put into it). 5. Potential energy decreases in its relation between its height above earth. 6. Work done on an object and the potential energy it recieves are equal. 7. Work may cause a change in height or speed or both. 8. You determine the Mechanical energy of a system by finding the sum of potential energy and kinetic energy. 9. If energy is conserved, the object's energy turns into heat when it stops moving. 10. There is not always enough energy at hand if the total energy in the universe is always the same amount because there are useful forms of energy to useless forms of energy. 11. Objects start to move through other forms of energy. 12. Thermal energy is heat/kinetic energy of molecules.

Then, after we had gone over those 12, the period was over and the substitute told us to answer the last question (what is energy?) on our own. Do not forget to have the two worksheets we did for homework last week, with you tomorrow in class (the due date was changed until Monday).

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