Changes in the Concept of Mechanical Energy of 9th Graders through Pendulum Motion Video Analyse

2021 ◽  
Vol 71 (10) ◽  
pp. 855-863
Author(s):  
Jeong HYEON ◽  
Wonkun OH*
Author(s):  
Akhmad Yusuf ◽  
Ishafit Ishafit ◽  
Toni Kus Indratno

<p class="Abstract"><em>Panggon Lunjak</em> (trampoline) is one of the famous amusement parks among the people that we can use as a recreation to enjoy a pleasant sensation. Without us knowing the amusement park that we often encounter is actually the result of the application of science and technology, especially in the field of physics, because it is amusement park for student of science is a real laboratory or the giant laboratory that we can use as a study of physics concepts and as research materials. <em>Panggon Lunjak</em> (trampoline) motion is very close to the harmonic  motion where the resulting graph of the sinus so that on the graph will be in the analysis of  kinematics and energy phenomena, so that research on simple harmonic motion materials is not limited to research using pendulum motion and spring load motion which is often exemplified as research on harmonic motion. The purpose of this study is to analyze the physical aspects of <em>Panggon Lunjak</em> (trampoline) motion based on the laws of physics on the concept of kinematics and analyze energy, Where the mechanical energy of addition between potential energy and kinetic energy (Conservation of energy). The analysis is done by using video tracking. Based on the analysis done using people as a mass, the result of the amplitude, the spring constant, angular frequency, and the law of conservation of energy on the <em>Panggon Lunjak</em> (trampoline) is true. This analysis activity will be well used as a physics learning for students.</p>


2020 ◽  
Vol 64 (1-4) ◽  
pp. 729-736
Author(s):  
Jincheng He ◽  
Xing Tan ◽  
Wang Tao ◽  
Xinhai Wu ◽  
Huan He ◽  
...  

It is known that piezoelectric material shunted with external circuits can convert mechanical energy to electrical energy, which is so called piezoelectric shunt damping technology. In this paper, a piezoelectric stacks ring (PSR) is designed for vibration control of beams and rotor systems. A relative simple electromechanical model of an Euler Bernoulli beam supported by two piezoelectric stacks shunted with resonant RL circuits is established. The equation of motion of such simplified system has been derived using Hamilton’s principle. A more realistic FEA model is developed. The numerical analysis is carried out using COMSOL® and the simulation results show a significant reduction of vibration amplitude at the specific natural frequencies. Using finite element method, the influence of circuit parameters on lateral vibration control is discussed. A preliminary experiment of a prototype PSR verifies the PSR’s vibration reduction effect.


2020 ◽  
Vol 3 (1) ◽  
pp. 51-53
Author(s):  
Rano Azizova ◽  
◽  
Umida Shamsiyeva ◽  
Mirzohid Turabbayev ◽  
Begzod Jorayev ◽  
...  

Traumatic brain disease (TBHD) is a pathological process triggered by the damaging effect of mechanical energy on the brain and is characterized — with a variety of clinical forms — by the unity of etiology, pathogenetic and sanogenetic mechanisms of development and outcomes.


1991 ◽  
Vol 56 (9) ◽  
pp. 1856-1867 ◽  
Author(s):  
Zdzisław Jaworski ◽  
Ivan Fořt

Mechanical energy dissipation was investigated in a cylindrical, flat bottomed vessel with four radial baffles and the pitched blade turbine impeller of varied size. This study was based upon the experimental data on the hydrodynamics of the turbulent flow of water in an agitated vessel. They were gained by means of the three-holes Pitot tube technique for three impeller-to-vessel diameter ratio d/D = 1/3, 1/4 and 1/5. The experimental results obtained for two levels below and two levels above the impeller were used in the present study. Radial profiles of the mean velocity components, static and total pressures were presented for one of the levels. Local contribution to the axial transport of the agitated charge and energy was presented. Using the assumption of the axial symmetry of the flow field the volumetric flow rates were determined for the four horizontal cross-sections. Regions of positive and negative values of the total pressure of the liquid were indicated. Energy dissipation rates in various regions of the agitated vessel were estimated in the range from 0.2 to 6.0 of the average value for the whole vessel. Hydraulic impeller efficiency amounting to about 68% was obtained. The mechanical energy transferred by the impellers is dissipated in the following ways: 54% in the space below the impeller, 32% in the impeller region, 14% in the remaining part of the agitated liquid.


Author(s):  
Dawn N. Castillo ◽  
Timothy J. Pizatella ◽  
Nancy A. Stout

This chapter describes occupational injuries and their prevention. It describes in detail the causes of injuries and epidemiology of injuries. Occupational injuries are caused by acute exposure in the workplace to safety hazards, such as mechanical energy, electricity, chemicals, and ionizing radiation, or from the sudden lack of essential agents, such as oxygen or heat. This chapter describes the nature and the magnitude of occupational injuries in the United States. It provides data on risk of injuries in different occupations and industries. Finally, it discusses prevention of injuries, using a hierarchical approach to occupational injury control.


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