Physics: 6: 5-7 Conservative and non-Conservative Forces

Homework

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

Reading Preparation

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

Study Points

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.

Key Equations

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

Web Lecture

Read the following weblecture before chat: Conservation of Energy

Study Activity

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.

Use the Guided Energy Loss Lab 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 included in the exercise to graph your data.

Chat Preparation Activities

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.

Chapter Quiz

The chapter quiz is not yet due.

Lab Work

If you want lab credit for this course, you must complete at least 18 labs; you may complete more if you are preparing for the AP exam.. 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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Physics

Chapter 6: 5-7 Assignment