1. HW #2 and Lab Activity #1 extensions – Thursday and Friday, respectively Lab Activity #2 (A3-FLOB) due Friday Exam #1 (Chs. 1 & 2) Thursday Read through to p.63 for next Tuesday Tuesday, February 5 Spring 2008

2. Energy Chapter 3 Great Idea: The many different forms of energy are interchangeable, and the total amount of energy in an isolated system is conserved.

3. Energy Definition: the capacity to do work A system can gain or lose energy if work is done on it or by it An abstract concept – we can only quantify it using mathematical formulas Analogies: Feynman’s toy blocks; money

4. Work Work is done when a force F is exerted to move an object over a distance d W = F × d unit of measure: the joule (J), 1 J = 1 N·m Energy is expended when a force acts over some distance to move an object Not all forces do work

5. Mechanical Energy Work done on an object is equal to its change in mechanical energy: W = Δ E M = Δ E K + Δ E P

6. Kinetic Energy Energy possessed by an object due to its motion Directly proportional to mass and square of speed of object Equation: E K = (½)mv 2

7. Gravitational Potential Energy The force of gravity gives the object the ability to do work Equation: E P = mgh Directly proportional to weight of object and height of its position

8. Potential Energy Energy possessed by virtue of an object’s position Stored energy that could result in exertion of a force  Gravitational potential energy  Chemical potential energy  Electrical potential energy  Elastic potential energy  Magnetic potential energy

9. Chemical – energy stored in chemical bonds of molecules Non-Gravitational Forms of Potential Energy Electrical – energy stored by stationary electrically charged particles in electric force fields Elastic – energy stored as a result of deformation of an elastic object Magnetic – energy stored by stationary magnetic objects in magnetic force fields