Electric Dipole and Torque (10th Day)

Spring 2015
Professor Mason
March 26 class

Electric Dipole
In class, we needed to draw an electric field horizontally and give the direction of where it will go in between two bars containing one negative bar and one positive bar, [a = qE/m].

As for electric dipole, the dipole moment [p = 2aq].

We needed to sketch the forces on each particle on the picture with three lines shown. After that, we found out there was a torque, and we needed to calculate it by using torque equation shown below.




Torque
We found out that torque has positive and negative forces, which could be combined into [T net = 2Fa sin theta] or [T = pxE] and [Uf = -pE cos theta] or [ Uf = p . E (dot product)]. Other equation that we used was [W = pE (cos theta i - cos theta f)].

Flux

Flux is defined as [Flux = EA cos theta], which E is electrical field and A is area. Net flux = Rate in - Rate out = 0. We were given a positive charge in between the flux lines, and we needed to find which direction it would go. In the end, we needed to do coding in VPython, which requires a lot of work, but we did not take any pictures of it.

Electric Field (9th Day)

Spring 2015
Professor Mason
March 24 Class

Definition of Electrical Field

 The first thing we learned in class was to define Electrical Fields. The picture attached shows the four definition of electrical fields along with the equation, which is [E = kq/r^2].
There are four steps to help remember the calculation/equation of electrical fields, which is shown in the picture attached below.

 Force on charged particle in an electric field, [F = qE].

Electric Field has field lines; field lines point out of positive charges and into negative charges (infinite lines on the charge). It uses the lines on charge to calculate the magnitude.






Super Position Principle
Super Position Principle is the complicated version of defining waves, which means that two waves that added together, and it works in electric fields (vector sum of the forces), [E = E1 + E2].

In class, we did some calculations about this equation, and some of them requires Microsoft Excel in order to do the calculation to make them easier to calculate. We used [r hat = vector r2 - vector r1 divided by magnitude of r2-r1 that will equal to just r], so it becomes [E = kq(vector r2 - vector r1)/ r^3]. The picture attached below is the calculation we did on Microsoft Excel.

VPython

In class, we were given a code from the lab book or we could also find it on profmason.com, and we needed to draw the diagram based on the code. The picture attached shows the diagram we made based on reading the given code.

VPython Assignment

Spring 2015
Professor Mason
VPython assignment

In class, Professor Mason, gave us an assignment, which involves VPython program in order to do 3D modelling. The steps are:
1. Go to vpython.org
2. Download and install Python 2.7 and Vpython by the "Windows" tab.
3. Open VIDLE for Vpython in my directory to start the program.

The first assignment I need to do is to code vectors of sphere and give them arrows, such as:

Next, I need to add # before "arrow" and pick one arrow length to be shorten by half. (*Note: Due to the unseen arrows because it was too short, I put more length to all of the arrows).

Next in the assignment, I need to do a 3D model, which I need to name the variables on each sphere.

Next, I was asked to add twice of one of the y-axis in the vector to the code.

The last part of the tutorial was about placing the  [print] command, which is written as print(variable,attribute).

Electrostatic Forces (8th Day)

Spring 2015
Professor Mason
March 19 class

Static with Balloon and Charge
Firstly in class, we learned about static that involves with a balloon. The first experiment was  to rub balloon on hair, then it sticks to the glass because it produces statics. The next experiment was to rub the balloon on silk, then sticks it to the glass; as a result, it sticks just for a while because there is no as much static as while rubbing on hair. Next, we needed to define charge for 7-years-old student; the example of charge is magnet: one side of the magnet can stick with the different side of the other magnet.













Electrostatic on Scotch Tape

In class, we did another experiment including electrostatic; however, this time we did it with scotch tape. First, we need 4 scotch tapes with approximately 10 cm long. First experiment: put a strip of scotch tape on the table with the sticky side down, then curl over the end of each tape to make a non-stick handle. Then, we peel the tape off the table and bring the non-sticky side of the tape toward another tape. As a result, the tape sticks to each other.
Second experiment: we place two strips of tape on the table sticky side down and we label them "B" for bottom. We press another strip of tape on top of each of the B pieces; then, we label these strips "T" for top. We pull each pair of strips off the table and we pull the top and bottom strips apart; then, we put one "T" strips of tape toward another tape. As a result, they're both attracted.

Next, we put one "B" strips of tape toward another tape, and the result was they move away from each other. The same result goes with the interaction between a "T" and a "B" strips.
The idea is that the interaction between objects that have been rubbed is due to a property of matter that we called it charge, which contains negative and positive charge. Charge moves readily on certain materials, known as conductors, and  not on insulators. In conclusion, metals are good conductors, while glass, rubber, and plastic tend to be insulators.




Forces between Two Balls

In class, we did an experiment of two balls moving toward another involving electrostatic force. We were supposed to do this experiment on Logger Pro and analyze it based on the video given from the professor. The free body diagram of forces of the balls give us an equation of [Fx = F- T sin(theta)], which will equal to [T = W/cos(theta)]. There is also an equation which involves gravitational force between two masses m1 and m2 separated by a distance r, and that leads to an equation of [F = G (m1 m2)/r^2]. The F vs r graph is shown on the picture attached.

 We can compare when the ball move away from each other with the mathematical formulation of coulomb's law, which is [Fe = K r12 (q1 q2)/r^2], which r12 is a unit vector from q2 to q1, r^2 is the square of the distance between the two charged objects in meters, K is a constant that equals to 9x10^9 Nm^2/C^2, and q is the charge in coulombs. We used this formula to define the two balls as charge in coulombs as they move away from each others.

The next experiment after we analyzed the balls' movement was to make a graph out of it by making an equation by using manual fit.

Electrostatic Experiment

 In class, we did another experiment involving electrostatic machine. Professor placed some strips of paper on the machine to show that the machine is producing electrostatic if the machine is turned on. The strips of paper sorts of hovering in the air when the machine is turned on because there is a static on the machine. If we placed our hands on the machine, it would produce a static noise. The next one is that the professor place a rods that spins when the machine is turned on because the machine produces statics and it is conducted to the metal rods, so it spins.

Entropy and Engine in Thermodynamics (7th Day)

Spring 2015
Professor Mason
March 17 Class

Diesel Cycle & Entropy and Enthalpy
In class, we learned about diesel cycle and entropy. We started from diesel cycle first; we compared diesel cycle with motor cycle. In diesel cycle, the pressure keeps going, and it keeps compressing until the gas ignite, which means that the pressure is constant; while motor cycle's compression stops at a certain point which makes motor cycle less efficient, and the maximum power is lower.

We also learned about Entropy and Enthalpy in class, which each of them has its own equation. Entropy's equation is defined as [delta S = Q/T], which means that if we derived Q, it becomes [ds = dQ/T]. In class, we learned that Adiabatic process has its Q equals to 0, and it is also called Isoenthropic, which leads to delta S equals to 0 if Q is equal to 0. If entropy's equation has a constant P, the formula becomes [delta S = mC ln(Tf/To)]. The other part that we learned was Enthalpy, which has an equation of [delta H = U + PV], which U is equal to internal energy. In Enthalpy, we also learned that Cp is equal to [dH/dT]. Another form of Enthalpy's equation is [ Q = delta H = Int from T1 to T2 of mCp T dT].

Law of Thermodynamics

We had a review in class about Law of Thermodynamics. The first one defines that energy can't be created or destroyed; the second one states that energy can be created, but not with spontaneously destroyed, while showing the graph above. We also learned about Stirling engine and Brayton cycle, and we did some calculations based on the data we had.

Visible Stirling Engine
In class, Professor Mason showed us a visible Stirling engine, but with much smaller version. He states that this engine generate electricity from temperature difference. This is how it works: we put ice cube on top of the engine, and the bottom one with hot water, then it will spin like the picture attached below.

 After we put the ice cube on top and the hot water on the bottom, we removed the hot water, so it would be room temperature on the bottom and ice cube on the top, and it was still running. The steps of how this engine works are expansion, transfer, heat transfer contraction, transfer, and repeat. This engine has a double efficiency of solar panel by 23 percent. In class, Professor Mason also showed us a low temperature differential Stirling engine, which has those same steps as the smaller version. This is how the engine's strokes look like.

Two Stroke Engine and Wenkel Engine

In class, professor Mason showed us another two engines beside the Stirling engine, and those are Two Stroke Engine and Wenkel Engine. Two Stroke Engine is often used only for small machine, and it is less efficient because there are lots of fuel that are not burnt. This is how it looks like.

As for Wenkel engine, it is different from Two Stroke engine and Stirling Engine. The power rate ratio is bigger because it has more power stroke. The hard part of this engine is the direction of where the forces are going. The strokes are: Intake, Compression, Power, and Exhaust. This is what it looks like.

Calculations

In class, we did some calculations based on the data in the lab book involving those pictures shown above. 

 In class we learned that effectiveness is defined as a symbol c, while c is equal to the actual output of energy defined divided by max output of energy by reversible process. This leads to a formula, which happens to be [mc ln(Tf^2/Ta Tb) = mc ln (Tf/Ta) + 0 + mc ln (Tf/Tb)]; that concludes that [Tf^2 = Ta Tb]. There is also an equation that we learned in class, which was [delta s = mL/Tp], [Qc/W = Tc/Th-Tc], [Qc/Tc = Qh/Th], [W = Th Qc/ Tc - Qc], and [delta t = W/P], which [Qh = W + Qc] and [Qc = COP W].
 In class, professor also showed us an experiment involving bubbles coming from water and soap. Next, professor made another experiment with the bubbles; after the bubbles go up, he set it on fire, and what happened was it ignited and created a flame.

 

Heat Engines and Heat Capacity (6th Day)

Spring 2015
Professor Mason
March, 12th

Thermal Electric Cooler
The first thing we did in class was an experiment about a thermoelectric cooler, which involves boiling water and ice water. This thing works just like rooftop solar panels, and it is dependent on the sun because heat is the source.

As shown on the picture above, one side of the cooler is dipped into boiling water and the other one is dipped into ice water. Therefore, we can conclude that temperature difference make the motor starts or make electricity (the circle plate starts spinning with a certain direction). Next, we flip the sides of the cooler, and what happened was the circle plate went into the opposite direction.  The next thing we did was to take out the motor and plug in the power supply into the cooler. 

This time, we did not put the cooler into any water, however, by plugging in the cooler into the power supply, it makes some temperature difference out of electricity. Therefore, we can conclude that power supply can turn electricity into temperature difference because it is acting as a heat pump. 

Heat Capacity

In class, we learned about heat capacity; we started with molar heat capacity. Molar heat capacity is defined as heat per unit change of temperature [C = Q/delta T]. Molar heat capacity of the gas is defined by and equation [C molar = Q/ (n*delta T)], which n is defined as molar. 

 We define isobaric process by an equation [Q = n*Cp*delta T], which Cp is a constant that equals to [5R/2]. We also define isochoric process by an equation [Q = n*Cv*delta T] (noble gas), which Cv is a constant equals to [3R/2]. We also had an adiabatic process, which the equation can be simplified as [(delta P/P) + ((Cp*deltaV)/(V*Cv)) = 0]. For adiabatic process, we can say that Q = 0, which leads to a simplified equation of
[(Ti*Vi^2/3) = (Tf*Vf^2/3)].

Carnot Engine

In class, we discussed about an engine other than heat engine, which is Carnot engine. We were supposed to do calculations based on Carnot engine by using equations [Qc = nRTc ln(Vi/Vf)] and [Qh = nRTh ln(Vi/Vf)]. We can simplify those equations into [(Qc/Qh) = (Tc/Th)]. By using those equations, we needed to find delta E internal, Q, and W by making table based on the ABCD diagram on the picture above. 

Heat Engine Experiment

In class, we got to play with a sample of heat engine that professor Mason provided. 

 As professor Mason explained the heat engine, he stated that when the radiator in a car is cooled and the engine produces heat, it provides efficiency. The constants for heat engine are: Monoatomic [u = (3/2) NkT], Rigid diatomic molecule [u = (5/2) NkT], Vibrating [u = (7/2) NkT].
There are some steps in heat engine, and these are the following:
First, the TDC is pushed down, the valve opens, air and fuel are pulled in (Intake Cycle). Second, the valve closes, volume decreases slightly, pressure increase greatly, and temperature increases (Compression Stroke). Third, high pressure area, cylinder go down, pressure decreases, volume increases, but still has fairly high pressure, and ignition (Power Stroke). Fourth, valve opens, piston moves upward, and go back to intake cycle again (Exhaust Stroke). Based on all the steps above, the only process that does work is power stroke because the volume is positive/increased.
There are ways to increase Power output in an engine, and below are the following:
1. Increase cycle per second.
2. Larger volume of cylinder of the piston.
3. Increase maximum pressure.

Processes for ideal gas and second law of thermodynamics (5th Day).

Spring 2015
Professor Mason
March, 10th

Processes for Ideal Gas
In March 10th's class, first thing we learned in the morning was about the processes or conditions of an ideal gas, and those are Isothermal, Adiabatic, Isobaric, and Isochoric (Isovolumetric).  The simple things to remember all of those are: Isothermal has a Temperature (T) that is constant or don't change, such as cup of coffee, the temperature is constant and molecules move faster [Q = mLT]; Adiabtic has a heat (Q) that is constant or don't change; Isobaric has a Pressure (P) that is constant or don't change, such as [delta U = Q - W] or [W = P*delta V]; Isochoric or Isovolumetric has a volume (V) that is constant or don't change, so that the heat would be able to change.

Heated Rubber Band
In class, we did an experiment on rubber band, which what we did was heating the rubber band and predicted how it would happen. We predicted that the rubber band would expand, however, our prediction was not right, and it was supposed to be shrinking when heated instead because it is made of polymer.

The next thing after heating the rubber band was conveyor. By the method of heating the rubber band, we can also apply this method in conveyor because it can do the same work as heating rubber band does. There is a 4 step cycle that creates a cycle to bring the object from one conveyor to the next conveyor. That can work because the rubber band inside the conveyor is heated so it can make a cycle.

Efficiency
In class, we learned about efficiency, which has the definition of [(how much you want)/(how much you have to put in)]; for example, we put in heat, and get out the work done: [delta E = Q - W] = [Qh-Qc-W] or [W=Qh-Qc]. For instance, a block full of Qh turns into a block divided by 1/4 of work and 3/4 of Qc. The definition of efficiency is [e = W/Qh].

Theoretical Analysis of a Heat Engine Cycle

This heat engine cycle that we learned in class has the same method as the syringe with a heated empty beaker attached to the syringe. Back when we learned the experiment about the syringe, we knew that when the beaker has a room temperature surrounding it, the plunger of the syringe slides down slowly, vice-versa.

We did an experiment that involves the syringe as well. However, this time is about heat engine, and professor Mason showed us the graph of the experiment based on the pictures on the sides.

There are 4 points mentioned in the lab book, and we need to do a calculations and a diagram, as well as a E internal table based on the data. We also put an object, which was happened to be an eraser and a marker on top of the plunger. Then we need to increase all the volume data by 2 cc because we started off from 2 cc. We used point #3 because it is the closest one to the atmosphere in order to find [PV = nRT] and [Q = mc*delta T].

We found the Energy internal based on the data in the pictures. Before we calculated the E int, we need to find the Q and the W first by using [W = P (V2-V1)]. Then we can calculate E int using [3/2 (P*V)]. The data in the book shows that point #1 and point #2 has the same P, which is P = 1.02x10^5. Point #3 and point #4 has the same P, whic his P = 0.79x10^5. Point #1 and point #4 has the same V, which is V = 0.08. Point #2 and point #3 has the same V, which is V = 0.1. The work done = the area enclosed.

After we calculated all the data, we need to calculate the net work done, which we found to be 460J; [W tot = W1 + W2 + W3 +W4].