Homework

- Reading Preparation
- Key Equations
- WebLecture
- Study Activity
- Chat Preparation Activities
- Chapter Quiz
- Lab Work

**Text Reading**: Giancoli, *Physics - Principles with Applications*, Chapter 6: Sections 5-7

*6.5*: Since forces do work, they are associated with energy, but not all forces are associated with both kinetic and potential energy. When the work done to move an object is equal to the change in potential energy of the object, the force is conservative. If work done is greater than the change in potential energy, then some work must be expanded by non-conservative forces.*6.6*: Mechanical energy, that is, energy accounted for by Newtonian mechanics (motion and force) is the sum of potential and kinetic energy of a system. This energy is always conserved if the system is isolated.*6.7*: To solve problems involving mechanical energy changes, work, and forces acting over distances, we consider separately the changes in kinetic and potential energy.

- Non Conservative Forces $$\begin{array}{l}{W}_{\mathrm{net}}\text{}={W}_{C}\text{}+\text{}{W}_{\mathrm{NC}}\text{}=\text{}\Delta \mathrm{KE}\\ {W}_{C}\text{}=\text{}-\Delta \mathrm{PE}\\ {W}_{\mathrm{NC}}\text{}=\text{}\Delta \mathrm{KE}\text{}+\Delta \mathrm{PE}\text{}\end{array}$$
- Conservative Forces $$\begin{array}{l}{W}_{\mathrm{NC}}\text{}=\text{}0\\ E\text{}=\text{}\Delta \mathrm{KE}\text{}+\Delta \mathrm{PE}\text{}\end{array}$$ $$\begin{array}{l}\mathrm{KE}\text{}=\text{}\frac{1}{2}m{v}^{2}\\ \mathrm{PE}\text{}=\text{}\mathrm{mgh}\end{array}$$

**Read the following weblecture before chat**: Conservation of Energy

If we drop a ball and it bounces, each succeeding bounce is a bit lower. This guided exercise walks you through the "observation" of a bouncing ball. Using the pictures of the starting height and the bounce height, we can calibrate the ball's energy loss over time.

Click HERE to begin investigating how a ball loses energy as it bounces. There are five trials. You will need a paper and pen or a notepad program to capture your "observations" and a calculator to calculate the energys involved. Once you have your data, you will be able to use the graphing tool incuded in the exercise to graph your data.

**Forum question**: The Moodle forum for the session will assign a specific study question for you to prepare for chat. You need to read this question and post your answer**before**chat starts for this session.**Mastery Exercise**: The Moodle Mastery exercise for the chapter will contain sections related to our chat topic. Try to complete these before the chat starts, so that you can ask questions.

- The chapter quiz is not yet due.

If you want lab credit for this course, you must complete at least 12 labs (honors course) or 18 labs (AP students). One or more lab exercises are posted for each chapter as part of the homework assignment. We will be reviewing lab work at regular intervals, so do not get behind!

**Lab Instructions**: Spring Constants

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