Photogates: An instrument evaluation

Mosca, Eugene P.; Ertel, J.

doi:10.1119/1.15906

Cited by 4 publications

(2 citation statements)

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“…This allows each student to make his own video during the same experiment and analyse it by himself on the spot. Second, the direct reading of time and position means that no calibration is needed (including for the quoted program) to avoid errors, as in the experiments with photogates, for example [10,14]. Third, although the results obtained by the method we proposed were better when using an air track, we showed in separate experiments that Newton's second law can be verified using also a sufficiently smooth surface, so these experiments are within the budget of any school.…”

Section: Summary and Perspectivementioning

confidence: 81%

Precise measurements in mechanics using a moving light source and a smartphone

Goev¹,

Velinov²

2022

Phys. Educ.

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In this paper, we propose a simple yet generic and versatile method to measure the position of a moving body as a function of time. Apart from very basic equipment such as carts and wheels, only a laser pointer or a similar device and a smartphone are necessary. By attaching a source of light to a cart and video filming its movement on a horizontal plane under the gravitational force, the position of the cart as a function of time can be recorded without any calibration and using one of the many free apps. The obtained results for the cart acceleration under a constant force were in very good agreement with Newton’s second law. The inexpensive equipment and the possibility of taking data at very short intervals allow different experiments in mechanics to be performed, for example to demonstrate the conservation of energy and momentum in mechanics or to investigate complex movements.

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Section: Summary and Perspectivementioning

confidence: 81%

Precise measurements in mechanics using a moving light source and a smartphone

Goev¹,

Velinov²

2022

Phys. Educ.

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show abstract

“…The intervals measured by the time sensors are subject to unwanted or unexpected effects that can cause one sensor to systematically record slightly different time intervals from another. The origin of these variations may be associated with the numerical accuracy of the time recorded by the sensors; positioning of the light barrier that may not be properly perpendicular to the sensors; sensitivity of the sensors to the speed of the cart; peculiarities of the response curve of the sensors (different thresholds and asymmetries), etc [12][13][14]. Here, we will not enter into detail in discussing the origin of these effects, but we will analyze their impact on the kinematic quantities analyzed in sections 2 and 3.…”

Section: Analysis Of Systematic Effects On the Sensorsmentioning

confidence: 99%

Optimizing acceleration measurements using a single photogate

2021

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Measuring the acceleration of a glider on a slightly inclined air track is a typical activity in different experiments in didactic physics laboratories. In this paper, we discuss acceleration measurements derived directly from the quantity Δv/Δt, testing its reproducibility with several time sensors (photogates). Using a standard lab equipment we show that acceleration measurements using two photogates strongly depend on the photogates used and even on the distance between them, what can frustrate the goals of the experiment. The technical aspects behind that unexpected behavior can be partially overcome by working with a single photogate in a method where the glider is launched uphill and its speed is measured in the ascending and the descending motion. Using this alternative approach we were able to reduce discrepancies by a factor of 6, down to less than 1%. For both methods, the systematic errors between photogates surpass the statistical uncertainties for each photogate. Finally, we show that these discrepancies can be explained by an offset of the order of 1 ms in time measurements.

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The CALIOPE: A Computer-Assisted Laboratory Instrument Oriented to Physics Education

Mesquita¹,

Melo²

1996

Microcomputer–Based Labs: Educational Research and Standards

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Photogates: An instrument evaluation

Cited by 4 publications

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Precise measurements in mechanics using a moving light source and a smartphone

Precise measurements in mechanics using a moving light source and a smartphone

Optimizing acceleration measurements using a single photogate

The CALIOPE: A Computer-Assisted Laboratory Instrument Oriented to Physics Education

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