Ch6_SolimanoM

=toc Lesson 1 a= What is work? When a force acts on an object and causes a displacement, it is said that work is being done on the object. The three parts of work are force, displacement, and cause. Examples include a horse pulling a plow, or lifting weights. Negative work can also be done. Negative work is when work is done to hinder an object from movement.

How is work expressed mathematically? The mathematical equation for work is work = F * d * cos(theta). F is force, d is displacement, and theta is the angle between the force and the displacement vector. Or, the angle is the angle between the force and the displacement. Work is measured in joules. A joule equals a newton * 1 meter.

=Classwork 1/30/12=

=Lesson 2 (method 5)= The difference between Internal and External forces -Forces can be categorized as internal or external forces. External forces include the applied force, normal force, tension force, and air resistance force. Internal forces include the gravity forces, magnetic force, electrical force, and spring force.

Total Forces -When a net work is done on an object by an external force, then its total mechanical energy is changed. If the work is negative work, then it will lose energy. External forces are capable of changing the total mechanical energy of an object and are nonconservative. When the only force doing net work on an object is an internal force, the object's total mechanical energy remains constant. Instead, the type of energy is changed, and the total mechanical force stays the same. They are referred to as conservative forces.

Problem Answers Part 1 1. PE to KE, the ball starts at rest, and eventually has kinetic energy. 2. PE to KE, at the top of the hill, the skier is not in motion and has PE, until he moves with KE to point B. 3. KE to PE, the ball travels with KE, until it stops, having PE. 4. KE to PE, the falling man with KE is slowed by the stretching bungee. 5. PE to KE, the dart is at rest until it is propelled into KE.

Part 2 1. Work is +, as force and displacement are both right, gains motion, changing KE. 2. Work is +, the ball being hit changes its kinetic energy, because the height changes, PE is also changed. 3. Work is +, the nail's velocity is changed, and thus its KE. 4. Work is - because the road pushes back on the tires, and its KE is changed as it loses speed. 5. Work is +, her KE changes when she pushes from the block. 6. Work is +, his height changes so PE changes.

=Electric Bills= Name: Michael Solimano Physics
 * Why Do My Parents Tell Me to Turn off the Lights? **** J **

Estimate how much electrical energy you consume on a daily basis (ie: what does it cost my parents)
 * __ Objective __**


 * __ What to do? __**

Laptop Charger- 240 V 15 Watts Apple TV- 240 V 2.06 Watts Camera- 8.1 V Ipod Touch- 30 V 2 Watts Iphone Charger- 240 V .15 A Macbook pro- 218 Watts Clock- 6 Watts Pencil Sharpener- 120 V 12A Wireless Router- 150 Watts
 * 1) Identify 10 electrical appliances you use on a daily basis and identify their power rating (in Watts).

Power (in Watts) = AMPS x 120 volts.
 * 1) The power rating will be listed on the info label – typically on the back of or under the appliance. Often the power consumption is listed in terms of AMPERAGE (amperage measures the current of electricity consumed). The power rating (in Watts) may be calculated using the following formula:

For example, a 12 AMP vacuum cleaner uses 12A x 120v = 1440 Watts of power. Laptop Charger- 15 Watts = .015 KW Apple TV- 2.06 Watts= .000206 KW  Ipod Touch- 2 Watts= .0002 KW  Iphone Charger- 36 Watts= .0036 KW  Macbook pro- 218 Watts= .218 KW  Clock- 6 Watts= .0006 KW  Pencil Sharpener- 1440 Watts= 1.44 KW  Wireless Router- 150 Watts= .15 KW  Stereo- 50 Watts= .05 KW  Canon Camera- 8 Watts= .0008 KW


 * 1) Determine the total kWh (kilowatt-hours) of power that you consume with these ten appliances.

Laptop Charger- 9 hours Apple Tv- 1 hour Ipod Touch- .5 hours Iphone charger- 9 hours Macbook pro- 3 hours Clock- 24 hours Pencil Sharpener- .1 hours Wireless Router- 24 hours Stereo- 1 hour Canon Camera- .01 hours
 * 1) First estimate how many hours you use each appliance. For example, you may use your hairdryer every second day for 10 minutes – so on average you use it for 0.17h/d ¸ 2 = 0.085 h per day.

Laptop Charger- .0015 KW x 9 hours = .0135 kWH Apple TV- .00206 x 1 hour= .00206 KWH Ipod Touch- .0002 x .5 = .0004 KWH Iphone Charger- .0036 x 9 = .0324 KWH Macbook pro- .218 x 3 = .654 KWH Clock- .0006 x 24 = .0144 KWH Pencil Sharpener- 1.44 x .01 = .0144 KWH Wireless Router- .15 x 24 = 3.6 KWH Stereo- .05 x 1 = .05 KWH Canon Camera- .0008 x .01 = .000006 KWH
 * 1) Calculate the kWh used per day by multiplying the wattage of the appliance by the hours used (per day).

Total KWH = 4.399 KWH
 * 1) Finally, determine the total kWh you use per day.


 * 1) What does this cost your parents?


 * 1) Look at your household electric bill. Find two numbers:


 * 1) the total dollar amount due - $440.34
 * 2) kWh consumed that month. 2329


 * 1) Costs of Electricity.
 * 2) Calculate the average cost per kWh by dividing the dollar amount by the kWh consumed. This is approximately what each kWh costs your family. (Note: this figure includes fees and taxes, too). The cost will probably be between $0.10-$0.20 per kWh – depending on how much electricity you use. Electricity costs more if you exceed a certain usage. 440.34/2329 = .189
 * 3) You can also look this value up on the bill itself. .124
 * 4) Compare the two values. Why are they different? The total may not account for total KWH, and thus would reflect a higher cost when experimentally calculated.

4.399 x .124 = .545
 * 1) Multiply the kWh you use per day by the cost per kWh to determine what you cost your parents.

No, electricity makes everything run, and we should pay a premium for it. My daily cost was also only half a dollar.
 * __ Evaluate __**
 * 1) Does the cost of electricity seem like a lot to you? Discuss this with your friends.

My total cost is probably much higher. I did not account for my TV and other things that I use everyday that would have a large cost.
 * 1) Keep in mind that this cost only reflects ten appliances. What do you think your total cost actually is? Are there major appliances that you may have excluded from your list of ten that would make a big difference?

I can turn things off when I do not need them, and only use things until they are fully charged, and not let things idle and use energy.
 * 1) If you think your consumption is a lot – what can you change? Do you need/should change?

This activity opened my eyes to the costs of energy. I did not realize how much energy is used everyday, and the cost of this energy. I learned that some items use a great deal of energy, while others do not. I also learned that certain appliances consume varying levels of energy, and that different functions allow them to consume more or less energy. I will try to reduce my family’s energy bill by decreasing my usage of certain appliances, and turning off appliances when I do not use them.