Tenth Day

Spring 2015
26th of March's Class

We start the day learning of moment, which is the equivalent of torque in kinetics. This is how the equations were set up:

Then we expanded it to form the formula for Energy:

Professor Mason then tested our understanding of electric field by having two points with opposing charges fixed in a certain position, and he went around the lab to randomly draw a charge at random position on the whiteboard. We were supposed to make a guess on how the charge would move through the electric field. This was our board, and we got it right:

The charge that Professor Mason drew was the blue positive charge.

After that we spent a great deal of our time coding on Python, hence we had no images to show for this part.

After we were done with the coding practice for Python, Professor Mason introduced the concept of Flux to us. Flux going into the system is treated as a negative, while going out of the system is taken as positive.

Professor Mason then gave us this question, shown in the picture below:

Assuming that the cube is a system, and the blue arrows indicate the direction of the electric field being applied, we were supposed to guess how many faces would have 0 Flux, the answer are circled in pink. Then we were asked to find the Flux of the remaining faces using variables, and the answer is circled in yellow.

Ninth Day

Spring 2015
24th of March's Class

Today, we deal extensively on Electric Field.

We then had the rest of the day working closely with the program Python. Since my group was not aware that we had to bring in a laptop, we had to draw on the whiteboard what the model would look like based on our experience coding with the Python program.

This is what we came up with, and it was actually accurate other than the fact that the cylinders had to stretch out for the entire x, y and z axis.

I circled the cylinders for clarification purposes. The red cylinder is supposed to stretch for the entire y-axis, the yellow cylinder is supposed to stretch for the entire x-axis, and the pink cylinder is supposed to stretch for the entire z-axis.

We did bunch of coding with Python that we did not take a picture of. We were lent a member from another group who had the Python coding in his tablet.

Professor Mason then had us practice calculating electrical field with multiple point charges.

This was the solution he wrote on the board, I had no picture of a solution written by our group as we were lost, so we decided that the time would be better invested listening to the explanations given by Professor Mason than to wrestle with the concept ourselves.

After that, we had practice working with Excel for calculations. The working world would prefer that we be able to efficiently calculate with little mistakes in a short time, therefore practicing how to utilize readily available software would be beneficial instead of manually calculating numbers all the time. This is what the table looks like:

Eight Day

Spring 2015
19th of March's Class

We start the day learning about electrical charges. Professor Mason got a balloon and rubbed it with fur material, then sticks it to a glass. Once the balloon got into contact with the surface of the glass, it got attached to it for a few seconds.

Then we did a demonstration of electrical charges again with the use of scotch tapes.

This first video shows what happens when we bring together two tapes right after we ripped them from the tape dispenser. As they have a similar charge, they tend to repel each other.

The second video shows what happens when two tapes are placed on top of each other on the bench, and after we separate them, we bring them closer to each other. They hold different charges, and were therefore attracting each other.

The apparatus shown in the image above generates charge by rubbing a belt continuously inside the tube, which was then transferred onto a metal strip that transfers it again into the dome shaped head. This build up of charge generates static electricity.

Volunteers were asked to touch it, and those that did, had their hair rising up slightly. Professor Mason also placed an aluminium bowl on top of it, and it was repelled.

We then did a video analysis on electrostatic force of two metal balls, and created a graph of its electrical forces vs. separation distance. However, we made a mistake when entering the data, hence the graph was inaccurate. Below is the picture of the graph.

1) Yes, we were able to show that the force of electrical interaction between two charges is inversely proportional to the square of the distance between the charges. The shape of the graph shows us that the closer the two charges are to each other, the stronger their interaction.

VPython Assignment

Spring 2015
22nd of March

VPython
After following the tutorial video form Youtube, I tried to replicate the practice assignment:

And this is what I got:

The next step, they asked me to remove the other arrows temporarily by adding # to the beginning of the other arrows' command line. Then shorten the one I picked for half of its length, and make it point in the opposite direction than its original direction.

However, due to its length being shorter than the radius of the sphere it is in, it seemed to have disappeared. It is just hidden within the sphere as the radius of the sphere 'swallowed' the arrow.

Then the tutorial went on to teach how to name variables of our own by equating a name that we choose, to the command line. I was then tasked to replicate a 3D model:

This is the coding I came up with and its resulting 3D model:

What happens when we move one sphere twice as far from the y-axis? This is what happens when I input the coding:

The next part of the tutorial taught about the [print] command, which is written as print(variable,attribute). This is the result:

Seventh Day

Spring 2015
17th of March's Class

At the beginning of the class, we were introduced to a different type of engine from the one that we have always worked on. It is the diesel engine. It has a higher efficiency, and a different way of combusting the gas inside its cylinder; by massive pressure.

However due to its lower maximum power, which is inhibited by various factors, like the strength of the materials required to withstand the intense pressure, it is less popular than the Otto Engine.

We were also introduced to the concept of Entropy.

This red coloured mechanism is a model of Stirling Engine. It's main trait is its use of differential temperature as its source of power. The alternating temperature of the gas in contact with the metal plate is what drives the motion in this engine.

In the case above, we heated up the gas with hot water from the bottom.

Below is a short video of a Stirling Engine in action.

This website has a simple model for how the engine works: Stirling Engine

Another engine that was introduced is the Wankel Engine, which is commonly known as Rotary Engine. It uses the same 4 step cycle as Piston Engine, however it boasts a higher horsepower per gallon of fuel than the Piston Engine.

This website has a simple model for how the engine works: Wankel Engine

We were taught about COP, the Coefficient Of Performance for an engine. Then Professor Mason gave us an example about using Electric Heater and Heater Pump, and made us compare their results. The Electric Heater is much more efficient, however the Heat Pump is still more favoured as the price of gas is much cheaper than electricity.

Then we were given a question about a freezer.

The image below is how we attempt to answer the questions.

Heat Processes (Sixth Day)

Spring 2015
12th of March's Class

This is a thermoelectric cooler, it functions as a machine that changes heat energy into electrical energy through the difference in temperature. The bottom part of the apparatus has a metal plating in the shape of the letter 'U'.

Since it is in the shape of 'U', it has two ends to the metal plate. Each side is supposed to be immersed in water of different temperature for the apparatus to work. Using the difference in temperature, it can generate electricity that is subsequently transformed into kinetic energy. This can be seen as the hypnodisk attached at the top of the apparatus started to spin after some time in the water.

The professor then asked us to make a prediction of what will happen if the temperatures were switched. The image that is posted below shows our prediction.

We then found out that it turns out like our prediction. The hypnodisk would spin the other way if the position of hot and cold water is switched.

Professor Mason then brought out a machine that could supply electrical energy. He removed the kinetic portion of the thermoelectric cooler, which is the hypnodisk, and connected that machine to the thermoelectric cooler.

He was trying to demonstrate to us that the process can be done in reverse, that means that with a supply of electrical energy, the thermoelectric cooler could produce heat energy in the form of differing temperature in the metal plate.

Image attached below shows what he is doing.

Pink arrow shows the machine's portion that will be putting in electrical energy into the thermoelectric cooler.

Orange arrow shows the thermoelectric cooler with the hypnodisk removed. This is the location that electrical energy is supplied to the thermoelectric cooler.

Yellow arrow shows the metal plating that will generate heat. One of the ends would get hotter, while the other would get colder.

The professor then gave us real-life examples of how the technology of thermoelectric cooler has been used in the past. It was used as a source of energy for launched satellites. By placing a chunk of Uranium, the heat radiated from Uranium would be converted into electrical energy for the satellite.

However it's use has since been stopped since the amount of Uranium they used to place into the satellite would be equivalent to a small nuclear bomb. If the satellite had exploded while launching, it would have spread radiation over a large radius of area. Hence, its use has been stopped till recently, where they only use small amount of Uranium.

The image above shows the derivation of Cv, specific heat when the Volume would remain constant. This is the case only when the process is isochoric and the gases involved are monoatomic.

After getting the Cv, professor Mason wanted to teach us the way to derive Cp too, the specific heat ratio for when the pressure remains constant.

Using Work and Heat's equations, we describe the change in temperature in respective equations. After that, we equate them to each other, and single out the Cp.

Cp is then equals to [Q/(p delta V)]*R

By the relationships:
U = Q - (p delta V)
U = (3/2) nRT
(p delta V) = nRT

Q is then equals to (5/2) nRT

[Q/(p delta V)]*R then equals [(5/2) nRT] / [nRT] * R

The [nRT] cancels each other out, leaving Cp to equal (5/2)R

Professor Mason then guided us to derivate the Work Done in adiabatic process. The first step is to find an equation that can describe the final pressure of the process. We can do this by using the (PV initial) = (PV final), which will result in p final being described as (PV initial) / (V final).

Then we integrate it  and at the end of the integration, we would obtain the formula that describes Work Done in adiabatic process.

Professor Mason then gave us a sample problem to work on. And the image attached below is how we attempted to solve it, though it was really messy as there were a lot of workings.

Upon completion of the exercise, we were introduced to how the pistons work in an engine. There are 4 steps to completing 1 engine cycle. Intake, Compression, Power and Exhaust.

Intake
The intake valve opens up, and the piston moves down, pulling in the gas and increasing the gas' volume.

Compression
Intake valve closes, and piston is moving up, increasing pressure, decreasing volume.

Power
When the piston is close to the top, a spark plug would ignite the gas causing an explosion as the piston is moving down. As the piston is pushed down by the force of the explosion, the momentum opens up the exhaust valve.

Exhaust
The piston moves upward, pushing the expanded gas out into the exhaust valve.

Below is a short video that depicts how the piston works. (Partly)

Professor Mason then asked us how to increase the power output of an engine, and asked us to make a guess on it. The image below is how we answered his question.

2nd Law of Thermodynamics (Fifth Day)

Spring 2015
10th of March's Class

2nd Law of Thermodynamics

Today we began class by learning of 3 types of conditions for ideal gases. Isobaric [Constant Pressure], Isovolumetric [Constant Volume], and Isothermal [Constant Temperature]. We were asked to make a graph that shows our prediction on how the graph would look like based on the relationship of the other 2 variables that does not change.

We then made calculations based on the 6 questions given to us from the website []. The image below is how we attempt to answer the questions.

We were then given 4 different graphs and was tasked to predict which graphs would correspond to which type of condition. And we have to explain why the 3rd (Isothermal) and the 4th (Adiabatic) seem similar but are different.

Isothermal means that the Temperature remains constant. Therefore its PV = nR delta T, is just PV = nR, this is the resultant equation for the graph's curve.

Adiabatic involves heat, therefore the formula Q= mC delta T comes into play. Singling out the delta T, we have delta T = Q/(mC). Substitute that into the PV = nR delta T formula, and we have PV=nR[Q/(mC)]. Adiabatic type has negligible Q so its Pressure and Volume relationship can be written as PV=nR/(mC).

So when we put them in comparison, Isothermal is PV =nR, while Adiabatic is PV = nR/(mC). Therefore, it can be observed that the curve of the graph for Adiabatic would be steeper as it would be divided by an additional (mC) variable.

The professor showed us an experiment similar to the one on 26th of February. A water bottle would be hung from a rubber band, and then the rubber band would be heated up by  hair dryer. We predicted that the rubber band would expand, and the height of the water battle from the floor would decrease.

However, in reality it was contradictory from our prediction. The rubber band actually shrunk as it is a polymer, and as it was heated up, it curls upward, causing it to shrink in size.

We derived a different form of the efficiency formula.

We then attempted a heat cycle question about an engine. This can be found in the Lab Manual.

At the end, we end up with this table shown in the image right above.

The 2 image above shows the 2 different ways of finding Net Work on the cycle. The first one is by calculating all the components, while the other is by determining the area of the graph.

After that the professor attempted to replicate the experiment in real life. And we were supposed to calculate it in the same way we did the heat cycle question before.

We picked the 3rd point as our base PV = nRT as it has the closest Temperature to room temperature and Pressure in the room.