Chapter+6

=__Physics Classroom__= =toc=

Lesson 1: Basic Terminology and Concepts
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 * **What is Work?**
 * Work has been done when a force acts upon an object and causes displacement of that object. We must have force, displacement, and cause for work to occur.
 * **How can work be expressed mathematically?**
 * Work is equal to the net force times displacement times cosine of theta. There will never be work with a 90 degree angle between the force and displacement vectors.
 * **What must occur for there to be work?**
 * To do work, the force must cause displacement. Even if there is displacement, there may not be work done because the force may not cause this motion. If a waiter is holding a tray, normal force goes up, but displacement is horizontal, so no work.
 * **What is the meaning of negative work?**
 * When the displacement and force vectors are in the opposite directions, the force is hindering (not causing) the displacement. Theta is 180, and cosine of 180 is -1. This causes negative work values.
 * **What is the unit of work?**
 * The unit of work is a Joule. It is the same as 1 Newton-meter. Non-standard units include foot-pounds or kg*(m^2/s^2).
 * **Why must we use free body diagrams to calculate work?**
 * Since there may be several forces applied to the object, we must do a free-body diagram to properly calculate the work.

Lesson 2: The Work - Energy Theorem
//Part A://
 * **What are examples of an internal force?**
 * Normal Force
 * Friction Force
 * Applied Force
 * air Resistance Force
 * **What are examples of an external force?**
 * Gravity Forces
 * Magnetic and Electric Forces
 * Spring Forces
 * **What is a conservative force?**
 * External Forces are conservative. They keep the same amount of energy throughout the process.
 * **What is a nonconservative force?**
 * Internal Forces are nonconservative. They are capable of changing the amount of energy from start to finish.

=__Activities__=

Electric Bill Analysis
__1)__ __2)__ Total kWh = 22.5 kWh __3)__ Total Amount Due = $125.75 ; kWh Consumed in 30 Days = 744 Actual Cost per kWh = 11.10 cents per kWh 22.5 x .111 = $2.47 Cost per Month = 2.47 x 30 = $74.10

With this in mind, I realize that I am using a lot more power per month than I had thought I would have. After calculations, from just 10 popular appliances, I discovered that I cost $74.10 a month. This seems extremely high, especially since some of my classmates have been as low as $9.92 per month. There are definitely more items I use around my house (such as lightbulbs, oven, treadmil, etc...), but I would not say that these would be a major impact on the cost of my expenses. So I would say that I cost, in total, about $80 a month, which is still ridiculous considering the total bill for that month was $125.75. However, I can easily change things to make myself more cost efficient. For example, if I can just get through my mornings without a cup of coffee (perhaps tea instead), then I cut down by $0.53 every day, which totals to 16 dollars in a month! With this in mind, I definitely need to change so I can help my parents save some money, which they can, in-turn, put that money towards something more productive, like my college fund!