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Section 2. Innovations in Education
DOI: http://dx.doi.org/10.20534/EJLL-17-2-6-9
Vinh Le Van, Ph.D. Student Vinh university, Vietnam E-mail: levinh.47aly.bs@gmail.com
Installation and use of laboratory equipments in teaching the "Mechanical oscillation" chapter
Abstract: Physics is the science of experiment, teaching the content, unit of knowledge by empirical method should be prioritized. The "mechanical oscillator" chapter is especially important for the 12th grade physics knowledge, in addition to providing students with types of mechanical oscillation knowledge, it is also knowledge base to absorb many units of knowledge, such as "mechanical waves", "Oscillation and electromagnetic waves" and "alternating current". However, when teaching this chapter by empirical method, teachers find it difficult to visualize the motion of vibrational types, if there are only experiments do not contain high scientific content.
Keywords: Harmonic oscillation, damped oscillation, constrained oscillation, consonance, experimental method.
1. Introduction
Physics is the science of experiment, teaching the content, unit of knowledge by empirical method should be prioritized. The "mechanical oscillator" chapter is especially important for the 12th grade physics knowledge, in addition to providing students with types of mechanical oscillation knowledge, it is also knowledge base to absorb many units of knowledge, such as "mechanical waves", "Oscillation and electromagnetic waves" and "alternating current". However, when teaching this chapter by empirical method, teachers find it difficult to visualize
the motion of vibrational types, if there are only experiments do not contain high scientific content. in order to overcome that, we have researched and installed a laboratory kit to teach the "mechanical oscillator" chapter, this lab kit allow to survey both qualitative and quantitative types of harmonic vibrations of single pendulum, pendulum Springs, physical pendulum, damped oscillation of single pendulum, pendulum Springs, constrained oscillation of single pendulum, the data is sufficiently large in a short time, the results are displayed graphically and easily observable, comparable and highly visual [1; 2].
Figure 1. The main equipment of the test kit
2. Constructing experiments on vibration types
2.1. Introduce device
Laboratories include: Motion sensor, constrained oscillation lab kit, single pendulums, a computer prein-stalled dedicated software, table clamp rack, protructor, physical pendulum, spring pendulum, hanger, intermediate connector va computer in figure 1 [4].
2.2. Experiment on vibration types
a. Survey of harmonic oscillation
Hang a single pendulum or pendulum spring to the rack after determining the length and weight of the
pendulum. Connect the pendulum to the small weights through a thread, hang the thread on the large groove of the motion sensor to transmit the pendulum's motion to the movement of the motion sensor axis. For physical pendulums, we can attach directly to the axis of the sensor. Make them oscillate with small amplitude. Computers will record the data obtained (After every 50 ^s, the machine records the data once).
Figure 2. Installation method and results of the experimental vibration oscillation of the pendulum spring
Figure 3. Installation method and results of the single pendulum vibration test
Figure 4. The installation and results of the experimental vibration measurements of the pendulum physics The layout and results of the experiment in Fig. 2, displacement, velocity and acceleration of the spring 3, 4. From the graphs and tables above you can see the pendulum, single pendulum and physical pendulum are
time varying with the sinusoidal law (Allow to display at the same time graphs of angular velocity and angular acceleration), from the data table, we can determine the period, angular velocity, angular acceleration of oscillation and calculates the linear velocity, linear acceleration of the pendulum. Teachers can also investigate the dependence of the single pendulum period on the length of the string. The dependence of the spring pendulum period on the mass of the object and the firmness of the spring. The dependence of the physical pendulum pe-
riod on the angle of inclination of the vertical vibrational plane. From there, gravity acceleration can be calculated at the site of the experiment. b. Survey of damped oscillation Installation as case ofharmonic oscillation, however, we wrap a lot of string around the axis of the motion sensor to increase friction. We performed with pendulum springs and single pendulum and obtained results as shown in Figure 5.
Figure 5. Installation method and results From the graph and data table above we can see the gradual dumping of single pendulum oscillations under the effect of frictional force similar to the theory. From there, it is possible to calculate the period, the amplitude reduction in a period and the registance force applied to the pendulum.
c. Survey of constrained oscillation Installation as case of harmonic oscillation, however, use the single pendulum of the constrained oscillation
of the pendulum dumped oscillation test test kit, as shown in Figure 6. Make the pendulum physically (in the constrained oscillator set in Figure 1) oscillate, It acts as an external force acting on a single pendulum. We surveyed and obtained the results as shown in Figure 6, From the graph and data table, we can see the similarity between theory and experiment. From this, it can be confirmed that the constrained vibration test is successful.
Figure 6. Installation and results 3. Using the experiments in teaching
In teaching physics, depending on the specific objectives and content of each lesson, teachers can choose different teaching methods. Here, we focus on empirical method, this is a relatively popular method and highly effective. Experimental teaching is conducted in a sequence of steps: Introduce the open-
of the forced vibration survey
ing event, exposing the available concept of students, Modeling — hypothesis, Infer the logical consequences, Propose experimental alternatives to examine logical consequences, conduct the experiments, measuring resultsUse model — hypothesis to explain, apply into reality and practice. In this process, using of appropriate experiments both in terms of intensity
and timing will have a great effect on students' cognitive activities [3].
Through the implementation process we would like to give some ideas as follows:
- Stage of the opening event: The opening event should be chosen as events that occur in reality, close to students life. Under permitted conditions, it is advisable to use realistic snapshots, video clips of related events to increase visibility.
- The stage reveals the available conception of students: During the physics classes, The most effective way to discover the concept of students with regard to things, phenomena are exploring is through discussion. Teacher should address the problem by using images close to real life, Lead the students boldly explained in their "experience", at the same time always show interest, encourage students even if the explanation is wrong with the knowledge of physics.
- Modeling-hypothesis: From the actual complex phenomena, Teachers use questions to help students predict the main causes, Major relationships dominate the phenomenons. The questions have to be logical in the sequence of the phenomena mentioned in the opening event.
- Assist students in deriving logical consequences: One of the basic requirements, that is the implication should be simple, can be observed or measured in practice.
- Construct logical test solutions for logical consequences: In fact, test experiments are not always available experiments, Instead, students can use experiments
with simple objects, often used in real life, sometimes these experiments are very effective because they are not complicated, Easy to implement and intuitive. For the lab kit installed, it is easy to check the logic, the results are visualized using graphs and tables. However, we should not make use of the computer connection lab kit as above (Students taking the lab steps will be less). In order to overcome this, it is necessary to have the skill in teaching the teaching of the teacher, For example, we only produce results in tables, ask students to draw graphs or mathematical expressions about the relationship between physical quantities.
— Consolidate and use: During this period, the teacher may suggest that students experiment with other experimental equiments or that other experimental options be available, this will promote positive, active in cognitive activities, Improving the ability to apply knowledge in the practice of students.
4. Conclude
With this kit, Qualitative and quantitative success of quantum oscillation of pendulum springs, single pendulum, pendulum physics, dumped oscillation of single pendulum, pendulum springs and forced vibrations with Outstanding advantages: Data recorded automatically after 50 ^s, Displayed in graphs and tables so the results are accurate, highly visual. It can be said that the construction of the lab kit used to teach the "mechanical oscillation" chapter in the 12th physics program has been successful, Contributing to improve the quality of teaching physics 12 in particular the quality of education in general.
References:
1. Duyen Binh Luong (editorial director), Quang Vu (Chief author). Thuong Chung Nguyen — Giang To. Chi Minh Tran — Quoc Quynh Ngo. 12th basic text book of Physics. Viet Nam Education Publishing House, — 2008.
2. The khoi Nguyen (editorial director), Thanh Khiet Vu (Chief author), Duc Diep Nguyen — Ngoc Hung Nguyen — Duc Tham Nguyen- Dinh Thiet Pham — Dinh Tuy Vu — Quy Tu Pham. 12th advanced text book of Physics. Viet Nam Education Publishing House, — 2008.
3. Duc Tham Nguyen, Ngoc Hung Nguyen (2001), Organize cognitive activity for students in physics teaching in high school, Viet Nam National University, Ha Noi Publishing House.
4. The manual uses PHYWE's physical pendulum experiments.
