Creative Work part 2

Last week we've already finished our creative work. We changed the values of our capacitors and inductors so that they will be close to each other. On the first try, the labquest showed a relatively good data compared to the last. It showed a sinusoidal wave function of voltage. When we tried it again, the results were not as good as the first. But nevertheless all the results in each run we made gives the sinusoidal wave we are expecting only that sometimes the period of the wave is not constant. These results may only because of the limitation of the detector we are using.

creative work part 1

We started our creative work last week. As I said before, our creative work is investigating the oscillations in an LC circuit. We used the labquest and voltage probe to see these oscillations. But what we saw is very far from what we expected. We expect something that is a smooth sinusoidal wave but we saw oscillations with varying amplitude through time. So next week we will try changing the values of the inductance of the inductor and capacitance of capacitor so that they will be close to each other. We suspected that the results we got is due to the big descrepancy in the values of capacitance and inductance we used.

Experiment 6 Electromagnetic Induction

The experiment is simple. We studied the relationship between a moving magnet and the current it induces in a wire specifically a solenoid.. we use the device called the galvanometer. The deflection of the needle in the galvanometer shows the magnitude and the direction of the current induced. We saw that the deflection of the galvanometer is very unnoticeable when we move the magnet towards the galvanometer slowly. When we drop the magnet in free fall towards the solenoid we saw a large deflection. Furthermore, we saw bigger deflection when we inserted another solenoid and iron bar inside the bigger solenoid. There are other ways to induce current like changing the current in the wire itself. By turning on and off the power source connected to the solenoid with another solenoid inside, we also observed deflection in the galvanometer.

Experiment 5: Magnetism

We did experiments on magnetism, We investigated the behavior of different kinds of magnet. We used a magnetic field sensor to determine the strength of magnetic field at any point around a magnet. When we did it, we only got two values at any point on a magnet. Maybe it's because we are using the sensor incorrectly or some other causes. But that part of the experiment is a failure for us. We also investigate the magnetic properties of a solenoid. We tried different radius of the coil of wire and we also inserted different materials in the solenoid.

RC Circuit

Last week, we continued our experiment on Capacitors. This time, we analyze the effect of resistor to the charge of the capacitor when they are connected in a circuit. A capacitor stores energy but the resistor takes away energy. We also analyzed what we called the time constant in charging and discharging the capacitor. We will also derive the formula of the relationship of current with the time constant. The experiment is just short so we finished early.

Experiment 4(Capacitors and Capacitance)

In this experiment we studied all about the capacitors and capacitance. The first thing we did was analyzing the structure of a capacitor which is so difficult because it is hard to break a small capacitors and see it's internal structure. The second part is to verify the effective capacitance of a charge capacitor that are connected in series and parallel connections. We are happ because the theoretical value is very close to what we got using capacimeter. The last part is to get a relationship between voltage, charge and capacitance. We can't really figure out how to do it because our problem is that the charge is an unmeasurable quantity. All we can measure is the voltage and capacitance. There will be a continuation of this experiment which is about the capacitor and resistor in a circuit. We will identify the behavior of an RC circuit. And, hopefully we can finally devise an experiment to determine the relationship between charge, voltage and capacitance.

Experiment 3(Kirchoff's rule)

This experiment is all about Kirchoff's rule. First we made some exercises on how to read voltage and current of resistors in a DC connection. Then we did the actual experiment. First I thought we will finish the experiment immediately but when we read the current reading in the resistors, we cannot find any reading. we replaced the multimeter suspecting there was something wrong with it but still nothing happens. we also replaced the wires but still the reading is zero.Then finally we had figured out that the resistance of the resistors are too big that when we compute for the current (I=V/R) the current is too low for the ammeter to read it.

Resistors and Ohms law

In this experiment, the main objective is to find the resistance of different materials. First, we get the resistance of a cylindrical ceramic resistor by the color codes int the resistor. Then we confirmed that resistance using ohmmeter. We also got the resistance and learned how to use the rheostat, resistance box, and variable resistor. We already knew how the resistance box works. But for the rheostat, we are not yet really sure what is the function of the probe.


We also got the equivalent resistance of cylindrical ceramic resistors in parallel and series connections. This is the part where we took some time because when we computed the equivalent resistance from the color codes of the resistor depending on what type of connection, the ohmmeter reading value is highly deviated from what we computed. So we have to do it all over again but still got the same results. We need to know why and what is the problem with that.

We also did circuit analysis for ohmic and non ohmic materials and compare the relationship of current and voltage between these two.

Electric potential and Electric field

Our first experiment in physics 102.1 is mapping equipotential lines. At first I don't understand and don't know what to do in this experiment because we were not yet taught by our professor the concept of electric field and electric potentials. By using the setup shown below, we can determine which parts of the electrolytic tank(dish of water) have equal potentials.

Connecting these points together what is formed is an equipotential line.Getting points with same potential or voltage is not that easy because we get some slight differences and at a certain point the electic potential fluctuates so we have to wait for the voltage to become steady. After having enough equipotential lines, we can get the electric lines of force which is perpendicular to the equipotential lines. And now the problem is how can I plot these lines in the computer.

Creative work

Our last experiment in physics 101.1 is an experiment designed by our own. We designed an experiment on conservation of energy. By using the set up below, we can verify that indeed the energy is conserved throughout the path of the ball. Energies included here are rotational and translational kinetic energy and potential energy.

The following data are obtained from the set up:

x1	x2	x3	<x>	sqrth	<x>
40.5	40.9	41.1	40.83333	5.932959	40.83333
36.7	36.9	36.4	36.66667	5.403702	36.66667
33.8	33.7	34.2	33.9	4.959839	33.9
29.9	30	30.3	30.06667	4.516636	30.06667
26	25.9	26.1	26	4.09878	26
20.9	20.7	21	20.86667	3.405877	20.86667
13.1	14	12.5	13.2	2.539685	13.2

And the graph obtained by plotting the distance versus the square of the height.

We can see that the fit of this graph is nearly linear as predicted by the equation of conservation of momentum where, the change in total mechanical energy is constant since friction does not do any work on the system.

Activity 7

Last week we did experiments on simple harmonic motion. We did experiments on a simple pendulum, a physical pendulum and a spring and mass system. All of these tree follows the equations for the simple harmonic motion: Simple harmonic motion is the simplest kind of oscillation. That is when the restoring force is directly proportional to the displacement from the equilibrium. Most oscillations that we observe are not just as simple as  simple harmonic motion but we can do approximate it as one. The picture on the right represents the setup.

By timing the period or the time it takes for one oscillation to occur, we can get some of the physical properties of the object like the moment of inertia of a physical pendulum. Errors in the data obtain may be caused by the large amplitude. Simple harmonic motion is only true for these cases for small amplitude oscillations. Here are the data obtained:

Simple Pendulum
Trial	Period		Length of string
1	0.947		22 cm
2	0.998
3	0.987
4	0.97
5	0.977

Spring and mass system
Trial	Period	mass
1	0.363	1000 g
2	0.356
3	0.377
4	0.353
5	0.361

Physical pendulum
Trial	Period	mass	length
1	0.927	43.3 g	33.9 cm
2	0.936
3	0.946
4	0.92
5	0.94

last week we've done an experiment on static equilibrium. We are to determine the magnitude of the normal force exerted by the fulcrum. Our set up is shown by the following representation:

We first measured determined where the center of mass of the beam by hanging it to the fulcrum and putting it in balance by adjusting the it's position. Theoretically since the beam is uniform, the center of mass should be in it's "physical" center. Then we are to hang some weights in it so that when we hang weights the beam will also balance. Also we move the weights in different distances from the fulcrum and making sure again that the beam will balance. We planned to make 5 trials but we only did one because it's so hard to balance the beam with weights. To calculate the normal force, the sum of net forces acting on the system (the beam, the fulcrum and the weights) should be equal to zero since it is not moving. Also the net torque acting on it that is measured from the left part of the beam should also be equal to zero.

Activity 2

Last two weeks, we did an experiment on projectile motion to test if the shape of the trajectory of an object undergoing projectile motion is really parabolic as predicted by it's equation. In order to do that we devised our own experiment using projectile guns and ramp. A projectile gun basically looks like this:

We set the angle at which we will fire our gun and let our metal ball hit the wall, leaving a mark on to it. Making the distance from the wall be our independent variable and the height at which the ball hit the wall be dependent variable, we can see that at some points the value of the height is lower and sometimes higher. It may look random when you can see the measurements but when we did the scatter plots of our values, and get it's curve fit, we saw that the path is really parabolic.
Here are the results that we got for 3 angles(15, 30, 45 degrees)

angle: 30 deg
initial y: 20.7 cm
x (cm)	y (cm)	uncertainty
50	39.6	0.1
60	41.75	0.25
70	44	0.6
80	45.45	0.15
90	45.95	0.55
100	44.8	0.4
110	42.55	1.65

angle: 15 deg
initial y: 20 cm
x (cm)	y (cm)	uncertainty
50	22.7	0.2
60	21.95	0.25
70	21.15	0.25
80	20.3	0.5
90	18.35	1.25
100	16.45	0.15
110	14.55	0.95

angle: 45 deg
initial y: 51 cm
x (cm)	y (cm)	uncertainty
50	88.55	0.05
60	94.9	0.1
70	99.85	0.05
80	101.8	0.3
90	104.8	1.2
100	107.5	0.6
110	106.25	0.4

For the angle of 30 degrees, we can see that it's y value increases as we increase the distance from the wall  up to 90. But at 100 cm, the values decreases. This means the maximum height the projectile reached is between 90 and 100. For the 15 and 45 degrees angle, the maximum height value is below 50 cm distance. Since we have the function of the curves generated from this values, we can get the exact maximum point by using some techniques from calculus.

Experiment 1

It's the start of "real" physics activities. We used a very high tech device than can produce an instant graph of velocity and distance over time from a detector of motion. It can produce the trend line of selected area of the graph. At first we detect the motion of a free falling ball and the motion of falling picket fence. A picket fence is a strip of glass with black stripes of equal spacing. As it passes through a detector, the detector detects how fast it is falling by detecting the motion of these stripes.

The first experiment, the free falling ball test is quite harder and sometimes give bad results. You have to throw the ball upward many times to get the result you want. Sometimes when your hand is exposed to the detector , you can get an unwanted result. The other one is quite easier because it gives a unique graph and is smoother compared to the one produced from the first one.

We did fifteen trials each test and all gives results of acceleration close to the value of g, the acceleration due to gravity. System error, and outside factors give small deviations from the real value.

January 9, 2011

We were taught on how to graph a scatter plot. A scatter plot should have an x and y axis labels and the units should be indicated, and the title (y vs. x). A caption may also be written. the range of the graph should be chosen for maximum readability. It means the points on the graph should not be too small nor too big. The y axis should be the dependent variable and the y axis should be on the x axis.
I also learned about how to put error bars on the graph that represents absolute uncertainties of a data point. the data points represents the expectation values. Below is an example of a scatter plot.

Trend lines and linear fits can also be drawn on the graph and the equation of the line should be written.

Activity 4

In this lecture we were taught how to get the measure of central tendency.. From a data set the mean of that data set would be the average value from the data set or the center of zero deviation. It means that subtracting each data from the data set to the mean and summing them all up you should get 0. The mode would be the "most frequent" data value. But mode can be more than one in a data set. so it is also defined as that data value that are at least as frequent as the other data value provided that not all data values are equally frequent.
The median is the "middle most" value. But for data sets that have even no., the median cannot be simply pointed out from the data set. And so, it was defined to be that data value such that at most 50% of the data is less than its least 50% of data is greater than or equal to it.
To get the coordinates (x,y) of the centroid which is the center  point of your scatter plot, the x coordinate would be the sum of all x coordinates of the all the data divided by the number of x. Same is for the y coordinate.
To get the best fit line, draw a line from the centroid to the origin and it will be represented by the linear equation y= mx + 0. The slope of the best fit line can also be found by getting the anything from these: ratio of medians, median of ratio, ratio of arithmetic mean, arithmetic mean of ratio, or regression through origin least square. All can give the exact value of the slope except for the ratio of arithmetic mean that can give a slight deviation from the actual value of the slope.

Activity 3

Calipers were the most precise measuring instrument I've ever used. We were taught how to use it in hiugh school and I've already forgot how to use it. One thing I've learned about calipers from this lesson is to how to fully utilize it's parts and functions to get a more precise measurement.Good thing we have physics 101.1. We had an activity on using calipers and I enjoyed measuring the thickness of 30 rice grains.

Activity 2

Wow! things get harder and harder. i thought on the first activity that it's all that we need to report data. But here comes activity 2. Error and error propagation. One type of error aside from the uncertainty was introduced. It's the deviation. And it makes things more complicated together with the addition of the absolute and relative errors. I've learned here how to add subtract, multiply or divide on best estimates. It's quite confusing because in adding or subtracting  you should use absolute uncertainty and in multiplying and dividing, relative uncertainty should be used. It also bacame harder when we computed multiple operations on best estimates. the differences between precision, accuracy, acceptability, and practicality are also explained. Then our professor gave us homework on other methods of estimates and errors. Because it uses statistics, I cannot understand many of these things.

Activity 1

It's the only time I really understood why we need the concept of significant figures. For example the value 2.3 is very differrent from the value 2.30 because 2.3 means not 2.2 and not 2.1. On the other hand 2.30 means that its not 2.29 and not 2.31. Uncertainty is always present when measurements are done based on the accuracy of the measuring tool that is why significant figures are really important. Another thing I only fully understood from this lesson is to how to find the significant figures of multiple operations. The part where we approximate the order of magnitude of the number of hair in the human person is the one  I really enjoyed. Fermi questions.... that's new to my ears and it sounds amazing especially when I heard that some people make it their hobby to approximate the magnitude of amount that are impossible to count. Another new thing is about the second order of approximation or the best estimate. Now I knew why trials are important to values that are changing and how to get the best estimate using the values from the trials. When the trials have values that are far from each other maybe you are doing somrthing wrong. That is why I also learned the technique to know whether you are doing the right thing in the experiment. Not like when I was in high scholol, we usually disregard the importance of trials and just give the value of the 2nd and other trials equal to the value of the 1st trial even though they were not exactly equal.

First day

As usual, we introduced ourselves and I introduced myself as a student from Benigno "Ninoy" S. Aquno High School, a not so popular school because it's just an ordinary public high school. I also said that I have chosen to be a physics major because of my teacher in physics and I want to prove that even if physics is a though subject, I can still do it. Then our professor explained what are we going to do for the rest of the semester. He explained the course outline. I didn't really understood all of it but one thing I know is that it will be going to be exciting as it goes on and our skill will be truly enhanced