Ch6_TomasofskyN

Chapter 6: Work and Energy

toc PC Lesson 1: Basic Terminology and Concepts
**Definition and Mathematics of Work**


 * What is work? How does it apply to motion?**
 * Analysis of motion
 * Mechanical Energy, Potential Energy, Kinetic Energy
 * __Work:__A force that acts upon an object to cause a displacement of the object
 * FORCE, DISPLACEMENT, CAUSE
 * forces must cause displacement
 * ex: pushing a grocery cart, carrying a backpack
 * [[image:http://www.physicsclassroom.com/Class/energy/u5l1a1.gif width="196" height="18" align="bottom"]]
 * F= Force
 * d= Displacement
 * Forces have to be kept separately
 * Vertical force can't cause horizontal displacement
 * Force angle is always parallel to incline
 * Displacement is also parallel to incline
 * __Negative Work:__ Doesn't cause displacement, but hinders it
 * __Joule__= unit of work
 * ** 1 joule = 1 Netwon * 1 meter **


 * How Do you calculate the amount of work done by forces?**
 * Follow Steps
 * Free body Diagram
 * Find the forces doing work on the object
 * Find the amount of work done by each force

=Classwork 1/30= PC: Work Energy Relationship

Internal vs. External Forces
 * External: Applied force (normal, tension, friction, air resistance)
 * Nonconservative forces: Capable of changing total mechanical energy ofn object
 * Internal: Non-contact (gravity, magnetic, electrical, spring)
 * Conservative forces: Capable of changing the form of energy but NOT capable of changing the total mechanical energy

Catergorizing Forces
 * How much does the force change an objects total mechanical energy when work is done to abn object?
 * Positive Work = GAIN ENERGY
 * Displacement and Force in same direction
 * Negative work = LOOSE ENERGY
 * (Kinetic/Potential/ Both)
 * Displacement and work in opposite direction
 * Work done = change in mechanical energy
 * Only internal forces
 * Mechanical energy (KE + PE) = constant
 * Energy conservation
 * Change from kinetic to potential (or vice versa)

Quick Quiz 1. PE --> KE 2. PE --> KE 3. KE --> PE 4. KE --> PE 5. PE --> KE 6. + KE 7. + Both 8. + KE 9. - KE 10. + KE 11. + PE

=How Much Energy Do I Use= Class Work: 2/8/12

Why Do My Parents Tell Me To Turn Off The Lights?

Household: 980 KWH Total Amount Due: $163.78

The cost of energy seems relatively low compared to the cost of other necessities, like gas or food. Although this is not extremely accurate, I consume about 71.142 KWH of per month. In total, my household consumes about 980 KWH per month. The wattage in my household is high because both of my parents work from home and therefore electricity is pretty much always being used. Even though there are a lot of things unaccounted for in my power usage, all in all I am not the main contributor to my family's energy bill. It is a good inference that most of this cost comes from things like heat and air conditioning. This would be more accurate if I included things like heat, the hot water heater, the refrigerator, or the garage door opener. As a whole, my family could save money and power by using less heat and energy and unplugging things that are plugged in all day. However, simply turning the lights or television off when leaving the room has been proven to not have the big of an effect on the electric bill.