1-30-09

Unfortunately, on Friday Mr. Manning was not in school. He told our class on Thursday that he needed to be home because his house was getting new carpet. Fortunately for us, our substitute was a former physics teacher, so he was excited to be back in the classroom and very avid about his job for the day. Mr. Manning left us with a video to watch for the class period, along with a worksheet with questions based on the content of the video. The video was about work and energy, which we started learning about this week. After the video was over, our sub. gladly went over the answers to the questions on the worksheet with the class. If you did not catch all of his answers, here they are:

1. When is energy conserved? **always** 2. What do we mean by Conservation of Energy? **energy is not created or destroyed** 3. How do we calculate the amount of work done when lifting an object? **W** =fh, or W= mgh 4. How does one calculate the potential energy of an object? **W=mgh** 5. How does an object's potential energy relate to its height above the Earth? **they are directly proportional** 6. How does the Work done on an object relate to the potential energy it receives? **they are the same** 7. Work may cause a change in **height** or **speed** or both. 8. What do we mean by Mechanical Energy? How do you determine the Mechanical energy of a system? **potential or kenetic, you add them** 9. If energy is always conserved, where does an object's energy go when it stops moving? **it dissipates its heat** 10. Why isn't there always enough energy at hand if the total energy in the universe is always the same amount? **its usefulness is gone** 11. If energy is always conserved, how do objects start to move? **take one form of energy and convert it to another** 12. What is Thermal Energy? **heat**


 * Reminder- the midterm and work & power worksheets are due for class on Monday!

An example of work being done!