Saturday, 1 December 2012




Data logger is an electronics instrument that records measurements of all types at set intervals over a period of time. Data logger also can record a wide variety of energy and environmental measurements including temperature, speed, light intensity, pressure, electric currents and more. The characteristic of a data logger is the ability to take sensor measurements and store the data for future used. This is how data logger works, a data logger works with sensors that then will convert physical phenomena and stimuli into electronic signals such as voltage or current. These electronics signals are then converted or digitized into binary data. The binary data is then easily analyzed by software and stored on a PC hard drive or other form of storage like memory card and CDs.
While we talking about data logger, data logging is the process of using a computer to collect data through sensors, analyze the data and save and output the results of the collection and analysis. Data logging is also implies the control of how the computer collects and analyzes the data. It is commonly used in scientific experiments and in monitoring systems where there is the need to collect the information faster than we do it manually especially when the experiments need accuracy. Figure below shows the complete data logging applications elements. 

A data logger has an additional recording and storage facilities. It can store readings from events taking days or week to unfold. Afterwards, the computer can read the data from it. There stand alone devices can often record data at high speed for example they can record the flicker of a lamp and take 100’s of readings in second. The data logger has buttons to start and stop according as well as an independent power supply. The buttons allow us to alter the recording speed when the recording would start. The data logger may have an LCD display to monitor what it is doing. In nearly every system that find, data logging sensors plug into a box. The sensor send its ‘readings’ to the box and informs it which type of sensor it is. The sensor identifies itself using pins on the sensor plug while some systems place a resistor across the pins and use its value to identify it. Others sensor have a PIC chip which ‘tells’ the data logger all it needs to know. Some sensors have their own power supply but the best derive all their power via the interface. Some devices get all their power through a USB connection o Parallel port and these tend to be the most reliable. The interface box has a circuit that converts an analogue sensor signal to a digital signal. It also has a way communicating with the computer and most systems use ‘serial’ communication. Serial connections are compatible with almost every type of computer. While this is not fast communication, they transfer data fast enough for most purposes. If we want to show sound waves with these data loggers, we can record the sound at high speed and transfer the data to the computer afterwards. Data logger can collect readings independently of the computer, allows results collected in the lab to be downloaded to the lab computer, can be set to start recording during the night, record very fast, can be set to start recording at a certain sensor reading and can store the results of many experiments. Data logger has a rechargeable battery and uses alkaline batteries.

In every PC data logging and controls system, there are few basic components which are sensors, connectors, conditioning, Analog to Digital (A/D) Conversions, Online-Analysis, Logging/Storage, and Offline-Analysis. A few additional components also required in a dta logging and Control system including D/A Conversions and actuators.

There are many type of sensors that are used in data logging. Sensors often process data before we can see it. The types of sensors that have are sensors to measure motion. Sensors that used to measure motion are accelerometer, light gates and switches, force or dynamic or mechanic pulley, rotation sensor, shock sensor, sonar distance sensor or ranger and strain gauge. The sensors that used to measure heat and temperature are heat flow sensor, full range temperature sensor, low temperature sensor, body temperature range sensor and thermocouple and high temperature sensors. Sensors for light and sound, we used light sensor, calorimeter sensor, infra-red sensor, sound sensor, microphone sensor, sound switch sensor and ultra-violet sensor. Sensors that used in physiology are pressure sensor, breathing monitor sensor, heart rate sensor and electrocardiogram sensor.
Any device that is used to convert physical parameters into electrical signals is called sensors. The sensors must be calibrated so that electrical output they provide maybe used to take meaningful measurements. For examples, flow meters, pressure transducers, accelerometers and microphone.  After we have the sensors, it must be connected to the connectors to transmit its electrical signal to the systems. There are variety of signal connectors that each have their own advantages and disadvantages. The simple connectors can be as simple as tightening a screw around a wire to the more complex like connectors typically used in NDT shown below.

Conditioning is the next steps needed for the electrical signal provided by the sensor to be useful. It is including all actions performed on the signal to improve its usability before it is digitized. There are few types of conditioning that can be used. Amplification is used when the voltage levels being measured are very small. Amplification is used to maximize the effectiveness of the digitizer. The typical sensors that require amplification are the thermocouples and strain gauges. Attenuation is the reverse of the amplification and necessary for measuring the high voltages. Filtering is the required to remove unwanted frequency components from a signal that will prevents the aliasing and reduces noise.

Excitation is used to provide the required currents and can be voltage or current source depending on the sensor type. Linearization is a type of sensors produce voltage signals that are not linearly related to the physical quantity they measuring. Isolation is used to in conjunction with attenuation to protect the system and the user from dangerous voltages or voltage spikes. It also can be used to when the sensor is on a different electrical ground plane from the measurement sensor. Lastly, multiplexing. Multiplexing allows you to automatically route multiple signals into a single digitizer. Most of the sensors required the combination of two or more of this conditioning technique like thermocouple.
There is also other components that build the data logging systems like A/D conversion that convert analog electrical signal into digital values and transmit those signal to the computer and these is done by the using the data acquisition (DAQ) board. Online analysis is used after the analog signal has been converted to raw binary values. For logging or storage ,PC based data logging systems generally use the hard drive of the PC to store data, but may also use tape drivers, network drivers, or RAID drivers. After that, offline analysis is the performing mathematical analysis on data after it has been acquired to extract information. There are two forms of control part of the PC system. The first one is open – loop control which is independent of the current state of the process and the second one is the closed-loop control in which the PC measures one or more input variables and uses software to make decisions about what control signals should be output. Other than that, there is also D/A converter which the function is to takes the digital values output by the computer and turns them into analog signals which can be conditioned and then connected to actuators. Actuators is any device that converts electrical signals to physical parameters. 
 People we ask why we use data logging. Data logging help us do a lot of things. Data logging help us to perform the experiments in a short time. If we do a manual experiments, we will take time to construct the apparatus, adjust the parameters, collect the data and to analysis the data. By using the data logging, we also can perform the experiments online and also perform the online analysis. For online analysis, this step will include any analysis that we could like to do before storing the data. The most basic example is, when converting the voltage measurements to meaningful scientific units, such as degree Celsius. We can complete these complex calculations and data compressions before logging the data. Controlling part of a system based on current measurements. Every data-logging software applications have to complete the conversions from binary to voltage and the conversions from voltage to scientific units. 
There is also step in data logging which is log that refers to the storage of analyzed data including any formatting required for the data files. When doing the experiment, it is very important to save all the data from the experiment, therefore by doing data logging, we can save all the data that need to be analyzed and also the format. Other than that, data logging also help you to do the offline analysis. Offline analysis is the analysis that we do after storing the data. For example, we can use the data stored to look for trends in historical data or data reduction.
Data logging also will help us by displaying, sharing and reporting the experiment that had be done. This application can save our time and also the experiment can be repeated over again to get the result that we need. This does not means the data logging application will prepare for you the full report of the experiment like the full writing report but it can help you to create any reports that need to make present the data. Data logging also can present the data straight from the online analysis. This means that the monitor able to display the data you need and also analyzed the data and also viewing the historical data.


Engage :

Last weekend, my family decide to go to Gua Kelam in Perlis. As we walk through the cave there is a lot of nice things to watch. Then, I notice something interesting, when we talk in the cave, we can hear our voice be reflect. We hear our own voice echo. Why this happened? I also notice the same phenomena occur when I talk in empty house or when I shout in the tunnel. How can this happen and what is the cause?

The speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at 20 °C, the speed of sound is 343.2 metres per second. In fluid dynamics, the speed of sound in a fluid medium either gas or liquid is used as a relative measure of speed itself. The speed of an object (in distance per time) divided by the speed of sound in the fluid called the Mach number.
The speed of sound in an ideal gas depends on frequency, but it is weakly depends on frequency for all real physical situations. Sound speed depends on pressure only because the air is not quite an ideal gas. For different gases, the speed of sound is inversely dependent on square root of the mean molecular weight of the gas, and affected to a lesser extent by the number of ways in which the molecules of the gas can store heat from compression, since sound in gases is one type of compression.
Speed of sound refers to the speed of sound waves in air and the speed of sound varies from substance to substance. Sound travels faster in liquids and non-porous solids compared in air. It travels about 4.3 times as fast in water, and nearly 15 times as fast in iron. Sound waves in solids are composed of compression waves just as in gases and liquids, but also exhibit a different type of sound wave called a shear wave, which occurs only in solids. The different types of waves in solids usually travel at different speeds. The speed of a compression sound wave in solids is determined by the medium's compressibility, shear modulus and density.

Sound is a longitudinal wave that is created by a vibrating object, such as a guitar string, the human vocal cords or the diaphragm of a loudspeaker. Moreover, sound can be created or transmitted only in a medium, such as a gas, liquid and solid. To see how sound waves are produced and why they are longitudinal, consider the vibrating diaphragm of a loudspeaker. When the diaphragm moves outward, it compresses the air directly in front of it. The compression causes the air pressure to rise slightly. The region of increased pressure is called condensation, and it travels away from the speaker at a speed of sound. The condensation is analogous to the compressed region of coils in a longitudinal wave.

Sound travels through gases, liquids and solids at considerably different speeds as shown in the table below:
Speed (m/s)
Air(0º C )
Air (20º C )
Carbon dioxide (0ºC )
Oxygen (0º C )
Helium (0º C )

Chloroform (20º C )
Ethyl alcohol (20º C )
Mercury (20 º C )
Fresh water (20º C )
Seawater (20º C )

Glass (Pyrex )


Near room temperature, the speed of sound in air is 343 m/s and is markedly greater in liquids and solid. For example, sound travels more than four times faster in water and more than seventeen times faster in steel than it does in air. In general, sound travels slowest in gases, faster in liquids and fastest in solids. Like the speed of a wave on a guitar string, the speed of sound depends on the properties of the medium. In a gas, it is only when the molecules collide that the condensations and rarefactions of a sound wave can move from the place to other place. It is reasonable, then, to expect the speed of sound in a gas to have the same order of magnitude as the average molecular speed between collisions. Sonar is a technique for determining water depth and locating underwater objects, such as reefs, submarines, and schools of fish. The core of a sonar unit consists of an ultrasonic sound, and at a later time the reflected pulse returns and is detected by the receiver. The water depth is determined from the electronically measured round-trip time of the pulse and a knowledge of the speed of sound in water. In a liquid, the speed of sound depends on the density and the adiabatic bulk modulus. For the speed of sound in liquid for example in seawater, the speed is 1522 m/s, which is more than four times as great as the speed in air. The speed of sound is an important parameter in the measurement  of distance. Accurate distance measurements using ultrasonic sound also play an important role in medicine where the sound often travels through liquid-like materials in the body. A routine preoperative procedure in cataract surgery, for example, uses an ultrasonic probe called an A-scan to measure length of the eyeball between the lens of the eye and the retina. When sound travels through a long, slender, solid bar, the speed of the sound depends on the properties of the medium.

Empower :

Ø  Equipment required
v  2 microphones-crystal Mics were used since they are cheap and give a large output
v  1 metre wooden rule
v  Fast digital storage oscilloscope-the ADC-212 was used
v  A balloon-to burst for a sudden loud sound source

Ø  Experiment set up

v  The experiment was set up as shown below with two crystal microphones placed 1 metre apart.

·         Result
·         The balloon was burst approximately 2 m away from the foremost Mic. The plot below shows the results clearly.
  The lefthand “BLUE” trace is from the foremost Mic (Mic1) and the righthand “red” trace is from Mic (Mic2)
  The waveform from Mic1 between -164µs and 500 s is clearly visible in the trace from Mic2 delayed by 2929 µs. There is second variation , in the waveform from Mic1, around 1.5 ms caused by an echo  from one  wall or ceiling. 

Enhance :
  Telling how far away a person with a starter’s gun, at a running race, is by comparing the time difference from when you can see the gun’s smoke to when you hear the sound.
  Telling how far away a cliff is by making a sound and measuring how long it takes for the echo to return
  Telling where an enemies gun was fired.
  Telling  how far away a lighting strike.

Friday, 23 November 2012

Stella Report

Title  :Pendulum story

Introduction :

Teaching and learning simulation

Simulation is the imitation of the operation of a real-world process or system over time. The act of simulating something first requires that a model be developed; this model represents the key characteristics or behaviors of the selected physical or abstract system or process. The model represents the system itself, whereas the simulation represents the operation of the system over time. A computer simulation is an attempt to model a real-life or hypothetical situation on a computer so that it can be studied to see how the system works. By changing variables in the simulation, predictions may be made about the behavior of the system. It is a tool to virtually investigate the behavior   of the system under study. Computer simulation has become a useful part of modeling many natural systems in physics, chemistry and biology, and human systems in economics and social science which is also known as the computational sociology as well as in engineering to gain insight into the operation of those systems. A good example of the usefulness of using computers to simulate can be found in the field of network traffic simulation. In such simulations, the model behavior will change each simulation according to the set of initial parameters assumed for the environment. The work builds on the established literature which highlights the importance of activities which make implicit reasoning explicit teacher guidance which builds upon pupils’ ideas and teachers interpreting shared experience to bridge the gap between scientific conventions and informal ideas. Thompson, Simonson and  Hargrave (1996) defined simulation as a representation or model of an event, object or some phenomenon. In science education a computer simulation according to Akpan and Andre (1999) is the use of the computer to stimulate dynamic systems of objects in a real or imagined world. Alassi and Trollip (1991) describe simulations in educational context that is  simulation is a powerful technique that teaches about some aspect of the world by limitating or replicating it. Students are not only motivated by simulations, but learn by interacting with them in a manner similar to the way they would react in real situations. In almost every instance, a simulation also simplifies reality by omitting or changing details. In this simplified world, the students solves problems, learn procedures, comes to understand the characteristics of phenomenon and how to control them or learn what actions to take in different situations.

Simulation can integrate into teaching and learning because simulations support learning by allowing a pupil to explore phenomena and handle experiments which would not be feasible in school.  Teachers can also focusing attention on underlying concepts and relationships. Simulations offer idealised representations that limit the range of operating variables to good effect. A teacher could focus on just one aspect of a concept, and be sure of always getting a good clean graph. Careful customization of resources might be needed to channel attention in a particular direction. Teachers used ICT to ease and speed cumbersome tasks. This enabled them to focus on the key ideas as well as making time available for discussing results. Data loggers displayed temperature readings so rapidly that pupils could analyse a pattern in a cooling curve graph. Normally they might only draw the graph. Teachers reported how hands-on such as simulation activities gave them time to interact with pupils. They could observe what was going on as they circulated, engaging learners in discussion and addressing their questions. Gathering information on pupils’ understanding is an important feature of teaching. The computer display enabled them to gauge progress readily. With a simulation, diagram or animation to hand, content was covered more quickly. Again, not having to draw repeatedly on the board, or handle physical apparatus, released time to concentrate upon learning, its consolidation and assessment. Students can build knowledge by integrating technologies . Teachers felt that technology could be used beside conventional practical experiments to enable students  to see what’s happening in the real world and what’s happening on the microscopic scale as well. Teachers would employ a visual aid or a practical demonstration in conjunction with a simulation. In some lessons teachers used technology to relate lesson content to prior learning and to reinforce that prior learning. This enabled students to engage with new activities. For example, pupils were expected to draw on graphical skills that had been developed in previous years. This skills training also helped to guard against misinterpretation of data logged graphs display and allowed pupils to make faster conceptual progress. In science process skills, simulations can activate process skill of students, which are the basic skills for scientific inquiry. These skills are classified in two main groups which are basic science process skills and integrated science process skills. Simulation can be used in distance learning education. The computer simulation make science accessible, make thinking visible, help students learn from each other and help students develop autonomous learning. In this case, students must have enough control lab equipment to start and stop an experiment and make appropriate adjustments. The experiment should be no more difficult to conduct than with the equipment physically present.

In simulation, the students will get motivation to carry out the experiment, for example we used stella, it can save our time and easy to do. We only need to run the experiment by adjusting the knob to vary the parameters to see any changes or differences between each parameters in the graph. So, when the students start interested to learn, their motivation to learn in order to get deep knowledge increase. Then, they can make prediction what will happen after carrying out the experiment by using simulation.

 The latest simulation in school nowadays is simSchool. This in an alternative idea for the preparation of teachers and the improvement of teaching which is simSchool is a “flight simulator” for teachers in the form of a simulated classroom game. The simSchool project addresses key systematic challenges of teacher education including fundamental conceptions of teaching and learning, organization of knowledge, assessment practices and results and engagement of a global community of practice in teacher education. Simulations provide multiple chances to practice and to learn and master new skills more rapidly and with less effort tha through experiences not mediated by computers. In teacher preparation, simulations that provide targeted feedback can develop teachers’ understanding and practice, and may be as effective as in classroom field experience. Students who practice with a simulator develop a deeper understanding because of their reliance on and experience of immersive multimedia.

Stella is System Thinking for Education and Research that offers a practical way to dynamically visualize and communicate how complex systems and ideas really work. Stella models provide endless opportunities to explore by asking “what if “ and watching what happens, inspiring the exciting moments of learning. Stella supports diverse learning styles with a wide range of storytelling features. Diagrams, charts and animation help visual learners or students discover relationships between variables in an equation. Stella is used to simulate s system over time, jump the gap between theory and the real world , enable students to creatively change systems , teach students to look for relationships and clearly communicate system inputs and outputs and demonstrate outcomes. The features os Stella are mappinmg and modeling, simulation and analysis and communication.


Simulation at school in Malaysia   provide students to learn the subject in deep learning. This is because they can understand about the topic that they learn because they can observe thoroughly the experiment. Simulations can be used as effective means for teaching or demonstrating concepts to students. The used of graphics and animation  help to build an interactive learning for students. For examples the uses of computer simulations in science education gives students the opportunity to observe a real world and interact with it. In science classrooms, simulation can play an important role in creating virtual experiments and inquiry. Problem based simulations allow students to monitor experiments, test new models and improve their intuitive understanding of complex phenomena. Simulations are also potentially useful for simulating labs that are impractical, expensive , impossible or too dangerous to run. Simulations can contribute to conceptual change and provide open-ended experiences for students. It also provide tools for scientific inquiry and problem solving experiences.


Objectives :

1) to understand the simulation that can integrate into teaching and learning.  

2) to understand the stella which is important for teachers and students.

3) to understand the concepts of pendulum.



Figure 1 :normal 


Figure 2 :mass of the ball


                                                     Figure 3 :initial displacement

                                                        Figure 4 :length of string

Discussion :

Simple pendulum is an excellent approximation of an isolated system. During its downswing, Earth’s gravity does work on the pendulum to transfer gravitational potential energy into kinetic energy .On the  upswing, gravity transfers kinetic energy back into gravitational potential mechanical energy of constant. The pendulum is a body suspended from a fixed point so as to swing freely to and fro under the action of gravity. Its regular motion has served as the basis for measurement, as recognized by Galileo.Huygens applied the principle to clock mechanisms. Other applications include seismic instrumentation and the use by NASA to measure the physical properties of space flight payloads. The underlying equation is at the heart of many problems in structural dynamics. Structural dynamics deals with the prediction of a structure’s vibratory motions. Examples include the smoothness or bounciness of the car you ride in, the motion that you can see if you look out of the window of an airplane in a bumpy flight, the breaking up of roads and buildings in an earthquake, and anything else that crashes, bounces or vibrates. With this pendulum motion as point of departure, complex structures can be analyzed. The pendulum serves as an illustration of Newton’s Second Law, which states that for every force there is an equal and opposite reaction. The simpler experiments illustrate another of Newton’s laws,namely, that a body in motion continues in motion unless acted upon by another force. The pendulum offers an extensive array of experiments that can be done using easy to obtain, inexpensive materials.The measurements require no special skills and equipment. The graphical results of each experiment  given, and can be compared to the results calculated from a simple equation if desired.

A pendulum is a weight suspended from a pivot so that it can swing freely.  When a pendulum is displaced sideways from its resting equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position. When released, the restoring force combined with the pendulum's mass causes it to oscillate about the equilibrium position, swinging back and forth. The time for one complete cycle, a left swing and a right swing, is called the period. A pendulum swings with a specific period which depends mainly on its length.  When given an initial push, it will swing back and forth at a constant amplitude. Real pendulums are subject to friction and air drag, so the amplitude of their swings declines. The period of swing of a simple gravity pendulum depends on its length, the local strength of gravity, and to a small extent on the maximum angle that the pendulum swings away from vertical, θ0, called the amplitude. It is independent of the mass of the bob. If the amplitude is limited to small swings,  the period T of a simple pendulum, the time taken for a complete cycle. For small swings the period of swing is approximately the same for different size swings: that is, the period is independent of amplitude. This property, called isochronism, is the reason pendulums are so useful for timekeeping.  Successive swings of the pendulum, even if changing in amplitude, take the same amount of time. For larger amplitudes, the period increases gradually with amplitude. The three different types of oscillation that are free, damped and fixed oscillation. Free oscillations occur while the pendulum is sets to its displacement and is moving in its to and fro motion it does not experience any force that prevents it from continuing this motion. Such forces that prevent free oscillation is,  air resistance. Damped oscillations occur while the pendulum is set to its displacement and is moving in its to  and  fro motion, experiences a force, or a medium that affects its motion. A forced oscillation occurs while an object is used to force or more pendulums into motion. An example of this is by using a driving pendulum to control the displacement of a set of 4 pendulums, which move as a result of the driving pendulum being displaced. Another example is using a vibrating tuning fork to force a stretched string to vibrate and set the pendulum into motion.

The aim of this experiment was to determine the   factors that  will affect the rate of oscillation of a pendulum, where oscillation is from the amplitude to the equilibrium to the amplitude. In order to find out the aim it is needed to find out the length, mass, or the amplitude, which are  factors, that may affect the rate of oscillation. The mass can be tested by changing the mass added onto the string while keeping the length of the string the same, and the amplitude of the string the same, which is   the amplitude is the distance from the equilibrium. In order to test the length, the mass and the amplitude are kept the same. And when testing the amplitude, the mass and the length are kept the same. For each of the factors tested the rate is needed to be calculated by figuring out the frequency and period. When the frequency is the number of complete oscillation in each second, and the period is the amount of time needed for one complete oscillation. The frequency is calculated by number of oscillation divided by the number of second in this case is 10 second. While the period is calculated by the number of second (10sec) divided by the number of oscillation. Once the pendulum starts to move, there are name for the aspects of its movement. The size of a swing is called the amplitude. The amplitude is measured in degrees, in which the same degrees that used to measure angles in geometry. One complete swing back and forth is called cycle . the time it takes for a pendulum to complete one cycle is called the period and the number of second is called frequency.

For the first graph is the normal one. During running the experiment, we do not change the parameter that is we only fix the mass of the ball which is the mass of the ball is 1.0 g , with initial displacement of  0.1 m and the length of the string is 1.0 m. The graph shown that the displacement or highest amplitude of the graph is 1.0 m with the gravity only. Then the parameter is changed with using the mass. The purpose that we manipulate the mass of the ball is we want to see the graph form and to know that whether the mass of the ball affect the period and frequency and amplitude of the pendulum motion.  So after running the experiment, it found that the period, frequency and amplitude is same when the different mass are used. The mass that are used are 0.50 g, 1.50 g, 1.82 g and 2.0 g. the driving force for pendulum is gravity. If the pendulum has twice the mass, gravity pulls twice as hard. Mass is also how hard the ball resists the force it feels. A pendulum with twice the mass feels twice the pull, but also has twice the resistance to that pull. These two effects balance out. A pendulum with twice mass still experiences the same effect. The mass of  ball does not affect how it moves. This is proven by the fact that in the equation v=2gh, the mass on both sides of the equation cancel each other out. For the second parameter we used initial displacement. The initial displacement 0.05 m, 0.12 m, 0.20 m and 0.12 m are use. When the initial displacement increase, the height of displacement also increases, the potential energy increases, so kinetic energy also increase but the time period remains same. For the third parameter, that is length of the string, with 0.5 m, 1.2 m , 1.6 m and 2.0 m. as the length of the string increases, so the period of the swing also increase. For the same linear amplitude, as the length increases, the displacement or height through which the ball  also decreases. Hence, when the height decreases, the kinetic energy will decrease, so also causing the potential energy to decrease. Velocity therefore decreases. When the velocity decreases, time or period will increases. When the length is increased to be longer, the frequency slows. When the length is increased N times, the frequency decreases by 1√N.

Last but not least, simulation play an important role in teaching and learning. This is because, the motivation of students to carry out experiment increases. Students only need to changed the parameter in stella in order to see the graph. They also can understand about the experiment very well instead of carrying out the experiment not using simulation. Students can relate the variables that can be made during the experiment. The teachers can also guide them in order to carry out the experiment. After doing the experiment, the students can expect what they learn about the experiment. So, they can relate the experiment and theories very well. 

Conclusion :

As a conclusion from the experiment, there are two factors that affect the period, frequency and amplitude of the pendulum. In this case, initial and length of the string affect the period , frequency and amplitude of the pendulum while the other parameter that is mass of the ball do not affect the motion of the pendulum. As the length of the string increases, the period of the swing also increases. , as the length increases, the displacement or height through which the ball   also decreases. Hence, when the height decreases, the kinetic energy will decrease, so  causing the potential energy to decrease, velocity  therefore decreases. When the velocity decreases, time or period will increases. When the length is increased to be longer, the frequency slows. When the length is increased N times, the frequency decreases by 1√N. For the initial displacement, when the initial displacement increase, the height of displacement also increases, the potential energy increases, so kinetic energy also increase but the time period remains same. For the mass, it does not affect the motion of the pendulum. A pendulum with twice the mass feels twice the pull, but also has twice the resistance to that pull. These two effects balance out. A pendulum with twice mass still experiences the same effect. The mass of  ball does not affect how it moves. This is proven by the fact that in the equation v=2gh, the mass on both sides of the equation cancel each other out.

Monday, 12 November 2012


Stella stands for Systems Thinking for Education and Research. The research and education are most exciting when we used STELLA in order to create, experience and see by ourselves  the experiment. STELLA  offers a practical way to dynamically visualize and communicate how complex systems and ideas really work.

In the ICT lab , we required to download STELLA and run the experiment. I was chose the pendulum story and we need to make a report about the experiment that we run. To run the experiment , we need to change the parameter in order to get the 4 different graph form and the first graph is we do not need to change any parameter. Here are the result from the experiment.  :