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= = =**Arvind Selva., Generation 2013**=


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Introduction Science and Society, December 2009 ||

=Complex Circuit 10/29/09=

//Find voltages Vai and Vah Vai=1.44 and Vah=2.82 Find voltages Vab, Vcd, Vde, Vfg, and Vgh Vab=1.40, Vcd=0.01, Vde=0.00, Vfg=0.00, Vgh= Find voltages Vac, Vbc, Vdf, Veg Vac=0.70, Vbc=2.11,Vdf=0.72, Veg=0.68 How does Veg + Vbc compare with Vbg? Veg+Vbc=2.70, and Vbg= What happens to Vbc if you put a clip from c to f?// The voltage for bc would stay the same because it's current from the battery is not changed. But the current for the other two light bulbs would not flow because the wiring has changed, by avoiding other wires connecting to the other light bulbs. What's going on with this circuit? **
 * Questions regarding the Complex Circuit

This can be a very confusing circuit, even for more advanced students. It turns out that electrical **//power//** through a bulb is the product of the voltage //across// the bulb and the current //running through// the bulb. For example, the electrical power through the first bulb could be calculated

P bc = V bc x I b

//**Check the power of each bulb by making these calculations. For the bulb between bc the power is about 0.7807. For the bulb between df the power is about 0.108. And for the bulb between eg the power is about 0.1768. **//

The **resistance** of a bulb is the ratio of the voltage across the bulb to the current through the bulb. For example, the electrical resistance of the first bulb could be calculated

R bc = V bc / Ib

For the bulb between bc the resistance is about 5.7027. For the bulb between df the resistance is about 4.8. And for the bulb between eg the resistance is about 2.6154. They are not the same. I am not really sure about the answer to why the numbers are different, but i will give the question a shot. Since bc had the highest voltage of all the bulbs, and a similar current to the other bulbs its resistance is greater. But for the df bulb and eg bulb the voltage are similar to each other but much less compared to Vbc. With these low voltages, and similar currents to all the other bulbs, when dividing the voltage by the current for the equation, df and eg currents have a smaller ratio to the voltage, as opposed to bc. But I still don't understand what the numbers from the equation are trying to tell me.
 * //Calculate the resistances of each of the bulbs in this circuit. Are they all the same? What do you think might be going on?//**

**Simple Circuit Diagrams 10/23/09** = = = = = = =Friday OCT. 23= 7.** A good conducter of electricity is also a good conductor of heat because it allows greater jostling of atoms, which also means higher temperatures, inside the conducter. =Wednesday OCT. 21= 1.** What is the difference between Proton, Neutron, and Electron? = = =  = =Thursday, Sept. 11= 2)** Velocitiy is the constant speed of a vehicle in the same direction. So when a friend says the car is turning at a constant velocity of 100km/h, is wrong because when the car is turming it won't be called vellocity. Instead the friend can say the car is turning at a constant speed of 100km/h.
 * //questions 7-12 and 19 from page 172 of your textbook (on electricity)//
 * 8.** When current flow into a lamb is increased, the brightness of the lamb will also increase.
 * 9.** You should consider getting a new tutor if the tutor says that ampere and volts are the same. Thats because amperes is the rate of electric flow and volts is the potential energy compared with the quantity of a charge. Amperes flow through a wire, but volts is the measure of the current.
 * 10.** figure one gives a current to the lightbulb because the wires connect too the bulb fromt the battery and back.
 * 11.** //If the same amount of current is travelling through the lightbulbs and the battery, why does a battery run out.//
 * 12.** Since a lightbulb uses such a small amount of current to make light, the rest of the unwanted current goes back into the battery to be sirculated throught the circuit again.
 * 19.** In the figure shown, bulb C is the brightest because it is the only bulb for the wire connecting to it, meaning all the current in the wire is for bulb C, also meaning bulb C draws the most current. Bulb A and B are not as bright as bulb C but still are identically bright to each other. That's because the wire is supplying for two bulbs instead of one. If bulb a is unscrewed, bulb B won't get any current, but if Bulb C is unscrewed nothing would happen to bul A or B.
 * //5 questions from ch. 9 studying//
 * 2.** What does Coulomb's first law mean?
 * 3.** Summarize polarization, and what it means?
 * 4.** How are Amperes, volts, and Ohms related and different?
 * 5.** Is the flow of current from the battery to the bulbs greater, than the flow of current back into the battery?
 * p. 35 "Think and Explain" 2, 4, 9, 13, 19
 * 4)** (has already been answered on the title of Thurs. Aug 27)
 * 9)** when on an high driving a car at constant velocity, the net force is zero, but you still need to run the engine for a few factors. Firt of all would be the wind pushing against your car, and secondly you have gravity and friction slowing down you car. Even though the net force is zero, you still nned to run the engine to equal the amount of force restricting your car to move.
 * 13)** If each rope on a scaffold has a tension of 200N, and you way 250N, then the weight of the scaffold wouldbe the two rope tensions minus your weight, which is 150N. This also allows you to achieve mechanical equilibrium.
 * 19)** When tossing a coin straight upward while riding in a train that is traveling straight, the coin will land in the same spot you tossed is from. That is because the inertia keeps the coin in uniform with your movement. When the train slows down, the coin will look as though it is moving forward, but itis actually you and the train which is slowing down. This occurs because the coins path is not affected to the stop due to no counteracting force, as when you on the train stops when the train stops. When turning, for example to the right, the coin will look as though it is moving to the left, but like before, it is just you and the train moving to the right.


 * p. 36 "Multiple Choice" 1-10**
 * 1)** a
 * 2)** b
 * 3)** c
 * 4)** b
 * 5)** d
 * 6)** c
 * 7)** a
 * 8)** a
 * 9)** d
 * 10)** c


 * p. 55 "Think and Explain" 2, 3, 5, 8, 9, 13, 14**
 * 2)** Your empty hand that crashed into a wall doesn't hurt, but if carrying and heavy load and crahing into a wall it hurts. This is because the intertia and weight of the object needs a stronger opposite force to slow it down. Meaning that your hand would hurt more trying to stop a heavy load quickly and a light load. This would relate to newtons third law.
 * 3)** When you crush a car into a compact cube you its volume but not its weight or mass.Weight and mass are realted. When you crush a car, it is still the sma e weight, meaning smae mass, but you decrease its surface are, which means that you reduced its volume.
 * 5)** If it takes 1N to push a book horizontally at a constant velocity, then the force of the friction is also 1N. Since the book is not travelling faster of slower but at the same velocity, menas the friction is equal to the movement of the book.
 * 8)** If two basketballs are dropped from a same height, and one baksetball is hollow and the other one is filled with rocks, the ball filled with rocks would travel faster. Gravity has the same amount of force pulling on them, but the heavier one would have a greater pull to earth due its weight, meaning that it would travel faster than the hoolow one.
 * 9)** When a parachutist has already opened her chute, and she feels like she is floating, the upward force is equal to the downward pull of gravity. The two forces are equal in magnitude that the parachutists will no longer gain speed but just maintains the steady speed down.
 * 13)** The terminal speed for a parachustist is greater before opening the parachute than after opening the parachute. Thats because before opening the parachute, the skydiver has less wind resistance allowing him to travel faster. But after opening the parachute his speed significanlty is slower thann before parachute was opened due to more wind resistance.
 * 14)** Before a falling body reaches terminal velocity the air drag of the body continues to increase before terminal velocity, After terminal velocity the airdrag stays the same because the body can't accelerate faster.


 * p. 55 "Multiple Choice" 1-10**
 * 1)** b
 * 2)** a
 * 3)** b
 * 4)** b
 * 5)** d
 * 6)** b
 * 7)** d
 * 8)** a
 * 9)** c
 * 10)** b

**Think about how the concept here relate to the motion of your car.** The concepts on chapter three relate to any vehicle in this world. The speed meters you see on your vehicle indicates how fast you are traveling in terms of acceleration. Acceleration is the change of velocity over time. when you turn or stop at traffic lights, you are changing your acceleration. Thats why the pedal that moves your car is called an accelerator. when you have a big heavy car, such as an hummer, it takes a bigger engine to move it. Heavy loads have a lot of inertia, meaning that it takes more acceleration to get an Hummer moving, and takes stronger breaks to stop and Hummer. = = = Wednesday, Sept. 2 Reading chapter 3, pages 38-43; Explain how to use your data to determine the acceleration of the cars you filmed; Write your best estimate for the car's maximum acceleration. Still under work = = = = Mon. Aug 31= 14) A scaffold weighs 300 N supports two painters, one 250 N and the other 300 N. The reading on the left scale is 400 N. What is the reading on the right scale?** The reading on the right scale would be 350 N. It is becuse the upward tension is equal to the sum of the scaffold plus the men. This makes the net force of the scaffold zero, giving it the name mechanical equilibrium. The readings of the scale should be half her original weight. Meaning that if you multiply the scales' reading by two, you get Nellie's weight. This method works because of the downward force of Nellie's weight, and the tension from both strings to hold her up. Initially, when the rope was attached around the chair, the weight of Harry's body was distributed between the two ropes. Since Harry weighs 500 N, the ends of the rope each hold 250 N. But when Harry ties around a loose end of the rope to a flag pole, the one end of the rope that is tied around the chair has to bear the weight of 500 N. And the breaking point of the rope is 300 N, so that is why Harry took an early vacation. = = =Thurs. Aug 27= **4) //If a huge bear was chasing you, its ennormous mass would be threatening? But if you ran in an zig zag pattern, the bear's mass would be to your advantage, why?//** The bear's mass would be to your advantage because it needs o apply more force to keep up the same speed as you. And since you are lighter than is, you are able to aply less force and easily shift your mass to run away from the heavy bear. Newtons' first law was basically that all object stay at rest unless a force pushes or pulls the object. And this ball is on top of the toy wagon. When the toy wagon moves forward, due to a force, the wagon will move in unison. But since the ball is at rest on top of the toy wgan, when the wagon moves forward the ball still stays motion less, but the wagon moves forward making the ball rest at the end of the wagon. When the bus is going at a certain speed and comes to a sudden hault, the bus has stopped but your are still travelling forward from the force that was pulling you and the bus. And for you to come to a sudden hault with the bus, you have to reduce that force quickly. When you are at a stand still on the bus and the bus suddenly picks up speed, the bus is moving forward but you are still in that initial position before the bus picked up speed. and that sudden lurch backward is due to the bus trying to push you forward with it. = __Tues. Aug 25__ = This link below contains my exel graphs on motion
 * Friday, Sept. 4**
 * page 36 answer questions 14-16 from Ch. 2 of text book
 * 15) Nellie Newton hangs at rest from the ends of the ropes. How does the reading on the scale compare to her weight?**
 * 16) Harry the painter swings year after year on his bosun's chair. His weight is 500 N and the rope, unknown to him, has a breaking point of 300 N. Why doesn't the rope break when he is supported? One day Harry is painting near a flagpole, and, ties the free end of the rope to the flagpole instead of to his chair. Why did Harry end up taking the vacation early.**
 * page 35 write questions 4, 6, 7 from Ch. 2 of science text book.**
 * 6)//Consider a ball at rest in the middle of a toy wagon. When the wagon is pulled forward, the ball rolss against the back of the wagon. Interpret this observation in terms of Newton's first law.//**
 * 7)//Why do you suddenly lurch forward in the bus that sudenly slows? Why do you lurch forward whent he bus picks up speed?What laws aplly here?//**