Atwood Machine [PDF]

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P-ISSN: 1693-1246 E-ISSN: 2355-3812 mm 2019



Jurnal Pendidikan Fisika Indonesia xx (x) (20xx) x-x DOI: xx.xxxxx/jpfi.xxxxx.xxxx http://journal.unnes.ac.id/nju/index.php/jpfi



DETERMINING THE ACCELERATION OF GRAVITY USING ATWOOD MACHINE PENENTUAN PERCEPATAN GRAVITASI BUMI DENGAN PERCOBAAN MESIN ATWOOD N. S. Anisah1*, A. Lu’lu 2, K. Bagas 3, A. P. Clarissa 4 1



Department of Physics Faculty of Mathematics and Science Universitas Negeri Semarang [email protected] 2



Department of Physics Faculty of Mathematics and Science Universitas Negeri Semarang [email protected] 3



Department of Physic Faculty of Mathematics and Science Universitas Negeri Semarang [email protected] 4



Department of Physic



Faculty of Mathematics and Science Universitas Negeri Semarang [email protected]



Received: dd mm yyyy. Accepted: dd mm yyyy. Published: mm yyyy Abstract This experiment aims to understand the working principle of the Atwood engine, conduct the Atwood experiment to show the validity of Newton's laws and determine the acceleration of gravity. The masses of the two weights will be M and m. The weights will be attached to hooks to stay connected to the string around the pulley. The weights will begin at rest but will be released, causing the pulley on the Atwood Machine to pull themasses, past the photogates, which will then calculate the time and acceleration. There will be six trials, where the time it takes the weight to reach the photogates will be recorded. The data will then be applied into kinematic equations to calculate the experimental acceleration. The accelerations will then be averaged together to acquire a mean acceleration, so as to have the most accurate data possible. We are likely to have some sources of error such as frictional forces in the pulley system.



Abstrak Eksperimen ini bertujuan untuk memahami prinsip kerja mesin Atwood, melakukan eksperimen Atwood untuk menunjukkan validitas hukum Newton dan menentukan percepatan gravitasi. Massa dari dua bobot tersebut adalah M dan m. Bobot akan dipasang ke pengait agar tetap terhubung ke tali di sekitar katrol. Bobot akan dimulai saat istirahat tetapi akan dilepaskan, menyebabkan katrol pada Mesin Atwood menariknya, melewati photogate, yang kemudian akan menghitung waktu dan akselerasi. Akan ada enam uji coba, di mana waktu yang dibutuhkan untuk mencapai photogate akan dicatat. Data kemudian akan diterapkan ke dalam



Jurnal Pendidikan Fisika Indonesia 11 (1) (2019) 1-7



persamaan kinematik untuk menghitung percepatan eksperimental. Akselerasi kemudian akan dirata-rata bersama untuk memperoleh akselerasi rata-rata, sehingga memiliki data yang paling akurat. Kami mungkin memiliki beberapa sumber kesalahan seperti gaya gesek dalam sistem katrol.© 2019 Jurusan Fisika FMIPA UNNES Semarang



Key words: atwood machine, acceleration of gravity, newton



INTRODUCTION



The pulley is rotated, if there is a frictional force so the equation will be :



Newton’s first law of motion, sometimes called the law of inertia, defines a special set of reference frames called inertial frames. This law can be stated as follows: If an object does not interact with other objects, it is possible to identify a reference frame in which the object has zero acceleration. Such a reference frame is called an inertial frame of reference. When the puck is on the air hockey table located on the ground, you are observing it from an inertial reference frame; there are no horizontal interactions of the puck with any other objects.(Serway, Jewwet:2008)



And we can get



The moves of masses from B to C is categorized as uniform lienar motion, and there is no acceleration in this system B to C.



We conclude that the acceleration of an object is inversely proportional to its mass. These observations are summarized in Newton’s second law: The acceleration a: of an object is directly proportional to the net force acting on it and inversely proportional to its mass. (Serway, Vuille, 2012:273).



We can determine the acceleration by formula



In the Si unit, with the mass in kilograms, the unit of force is called Newton (N), one newton the is the force required to import acceleration pf 1 m/s2 to a mass of 1 kg. (Giancoli,2005 :36)



The motion from A to B (there is M and m) its about accelerated uniform linear motion with its formula



METHOD The method of the experiments is : 1. Wighing masses of M1 and M2, also m 2.Determining the position of point A, B, and C, measuring SAB and SBC 3.Attaching the straps and weights, checking and try too get as little friction as possible 4. Attaching M1 to the clamps with springs S1 and (M2+m) in position A, then removing M1 from clamp,and writing the time



M1 moves with acceleration upward. M2 from point A to B, move accelerated downward



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required by (M2+m) from A to B or t AB and by M2 from B to C 5.Repeating above experiment for additional leads.



remains constant acceleration increases with the increase in net force acting on the system. The experiment still has an error from some factors. A majority of the sources of error were due to the frictional forces in the pulley system, also the masses of the weights might not have been exact, considering that the weight of the hooks attached to the masses wasn't identified and accounted for. Air resistance was a major player when the difference in masses was large, therefore acceleration was high. The weights could have been verified to eliminate that error, and more advanced physics could have been used to take into account the friction of the pulley and the air resistance. In light of these sources of error, which could have manipulated the results to be inconclusive, since the theoretical values were reasonable compared to the observed values, the connection between mass and acceleration, stated in Newton's laws, was solidified.



Tools and equipments of this experiment are : 1. Atwood machine 2. Technical ballance sheet 3. Two stopwatches



RESULT AND DISCUSSION The experiment show how Atwood machine’s work. The Atwood machine is using law of motion or Newton’s law. From the experiment we get the data that include in the table 1



Table 1. data of the experiment No 1 2 3 4 5 6



Mass (gram) 15.30 12.60 10.07 7.33 5.14 2.19



SAB (cm) 50 50 50 50 50 50



SBC (cm) 50 50 50 50 50 50



(s) 0.99 1.24 1.35 1.63 2.26 3.90



(s) 0.69 0.52 0.82 0.97 1.00 1.82



CONCLUSION Principle working of Atwood machine is using accelerated linear motion and unifrom linear motion based on Newton’s Law. The experiment show the effect of Newton’s Law in motion of the mass which is acceleration is depend on foces and masses. From it we can determine the price of acceleration of gravity.



From the data we can calculate the acceleration of gravity, by determining x axis and y axis after it count the value of its tangential diagram. For the moving of mass in A,B, and C must be calculate separately because of their base motion. Motion from A to B is an accelerated linear motion and the moves of mass from B o C is uniform linear motion without any acceleration. From the moves of the object from A to b we get the price of acceleration of gravity is 15.7 m/s2 . And from the moves of B to C we get the acceleration of gravity is 9.13 m/s2. Acceleration is directly proportional to the net force acting on the system. This was also shown by the inversely proportional relationship between the acceleration of the masses and the sum total of those masses. When the total mass



ACKNOWLEDGMENTS acknowledgments are directed to Mrs. Ellianawati as my lecturer, Mrs. Natalia as laborant, Dwi Ragil and Winda Naili as assistant of laborant and also all of my team.



REFERENCES Serway, raymond and Jewwet, John W. (2009) Physics for scientist and Enginers with Modern Physics. Belmouth, USA. Thomson Higher Education. Lecturer Team Basic of Physics 1, (2019) Buku Panduan Praktikum Fisika Dasar 1. Semarang, laboratorium Fisika Dasar Universitas Negeri Semarang.



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Serway, Vuille. ( 2012) College Physics. Boston, USA. Brooks/Cole Giancoli. (2005). Physics. USA. Pearson Education, Inc.



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