Translated 3.1.1-3.1.17
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| + | <meta name="author" content="Aliaksandr Melnichenka"> | ||
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| + | <body style=""> | ||
| + | <header style="text-align:center;"> | ||
| + | <div id = "logo"> | ||
| + | <span><img src = "../../img/book.png"><span><span>Savchenko Solutions</span> | ||
| + | </div> | ||
| + | <p class="author"> | ||
| + | Solutions of Savchenko Problems in Physics <br> | ||
| + | <i><b>knowledge must be free</b></i> | ||
| + | </p> | ||
| + | </header> | ||
| + | |||
| + | <h3 id="back-link"><a href="../../#3.1">$\leftarrow$Back</a></h3> | ||
| + | |||
| + | <h3> Statement </h3> | ||
| + | <p> | ||
| + | $3.1.4.$ Why does a rapidly oscillating bulb on a spring seem to flash at the extreme points of its trajectory? | ||
| + | </p> | ||
| + | |||
| + | <h3>Solution</h3> | ||
| + | <p> | ||
| + | </p> | ||
| + | <center> | ||
| + | <figure> | ||
| + | <img src="https://savchenkosolutions.com/3/3.1.4/animation.gif" | ||
| + | loading="lazy" width="350" /> | ||
| + | <figcaption> | ||
| + | Harmonic motion of a light bulb using a mathematical pendulum as an example | ||
| + | </figcaption> | ||
| + | </figure> | ||
| + | </center> | ||
| + | <p> | ||
| + | |||
| + | The power of the light bulb, and as a consequence the intensity of the light bulb, remains constant, so the longer the light bulb is at a certain moment, the more energy comes to the eye. Because the human eye perceives and accumulates light energy at a particularly high frequency of change (more details: <a href="https://doi.org/10.1016/S0042-6989(99)00084-X">doi.org/10.1016/S0042-6989(99)00084-X</a>), then the longer the body is at a certain point, the brighter it seems to the retina of our eye</p><p> | ||
| + | The perceived energy is inversely proportional to the time spent in a given place: | ||
| + | $$ W\sim\Delta t $$ | ||
| + | In harmonic motion, the position of the light bulb is described by the expression | ||
| + | $$ x(t) = x_0 \sin\omega t $$ | ||
| + | From here, the speed value changes as | ||
| + | $$ v(t) = \dot{x}(t) =\omega \cdot x_0\cos \omega t $$ | ||
| + | The lower the speed, the more time it takes for the light bulb to cover equal intervals of time. | ||
| + | $$ v\sim\frac{1}{\Delta t} $$ | ||
| + | Thus, when the speed of the light bulb during harmonic motion is minimal, the energy perceived by the eye becomes greater. | ||
| + | $$ W\sim \frac{1}{v} $$ | ||
| + | Thus, the bulb appears brighter in places where its speed is minimal, i.e. at its extreme points. | ||
| + | </p> | ||
| + | |||
| + | <p style="text-align: right; font-style: italic; font-size: 14;"> | ||
| + | Aliaksandr Melnichenka<br> | ||
| + | </p> | ||
| + | |||
| + | |||
| + | <footer class="row container"> | ||
| + | <br> | ||
| + | <p> | ||
| + | <small> © <strong>Savchenko Solutions</strong>, 2023-2024 <br></small> | ||
| + | </p> | ||
| + | <p> | ||
| + | <small>All rights belong to the authors. <br> Commercial use of materials - with the written permission of the authors. <br> alex@savchenkosolutions.com <br></small> | ||
| + | </p> | ||
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| @@ -0,0 +1,98 @@ | |||
| <!DOCTYPE html> | |||
| <html lang="en"> | |||
| <head> | |||
| <meta charset="utf-8"> | |||
| <meta name="viewport" content="width=device-width, initial-scale=1.0"> | |||
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| <meta name="keywords" content="Savchenko Problems in Physics, Savchenko solutions, physics problems, physics olympiad preparation, IPhO, Jaan Kalda"> | |||
| <meta name="description" content="Why does a rapidly oscillating bulb on a spring seem to flash at the extreme points of its trajectory?"> | |||
| <meta name="author" content="Aliaksandr Melnichenka"> | |||
| <meta name="date" content="2023-10" scheme="YYYY-MM"> | |||
| <meta property="og:title" content="Why does a rapidly oscillating bulb on a spring seem to flash at the extreme points of its trajectory?"> | |||
| <meta property="og:image" content="img/logo.png"> | |||
| <meta property="og:description" content="Why does a rapidly oscillating bulb on a spring seem to flash at the extreme points of its trajectory?"> | |||
| <meta name="yandex-verification" content="6cfda41f74038368"> | |||
| <title>Why does a rapidly oscillating bulb on a spring seem to flash at the extreme points of its trajectory?</title> | |||
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| messageStyle: 'none' | |||
| }); | |||
| </script> | |||
| </head> | |||
| <body style=""> | |||
| <header style="text-align:center;"> | |||
| <div id = "logo"> | |||
| <span><img src = "../../img/book.png"><span><span>Savchenko Solutions</span> | |||
| </div> | |||
| <p class="author"> | |||
| Solutions of Savchenko Problems in Physics <br> | |||
| <i><b>knowledge must be free</b></i> | |||
| </p> | |||
| </header> | |||
| <h3 id="back-link"><a href="../../#3.1">$\leftarrow$Back</a></h3> | |||
| <h3> Statement </h3> | |||
| <p> | |||
| $3.1.4.$ Why does a rapidly oscillating bulb on a spring seem to flash at the extreme points of its trajectory? | |||
| </p> | |||
| <h3>Solution</h3> | |||
| <p> | |||
| </p> | |||
| <center> | |||
| <figure> | |||
| <img src="https://savchenkosolutions.com/3/3.1.4/animation.gif" | |||
| loading="lazy" width="350" /> | |||
| <figcaption> | |||
| Harmonic motion of a light bulb using a mathematical pendulum as an example | |||
| </figcaption> | |||
| </figure> | |||
| </center> | |||
| <p> | |||
| The power of the light bulb, and as a consequence the intensity of the light bulb, remains constant, so the longer the light bulb is at a certain moment, the more energy comes to the eye. Because the human eye perceives and accumulates light energy at a particularly high frequency of change (more details: <a href="https://doi.org/10.1016/S0042-6989(99)00084-X">doi.org/10.1016/S0042-6989(99)00084-X</a>), then the longer the body is at a certain point, the brighter it seems to the retina of our eye</p><p> | |||
| The perceived energy is inversely proportional to the time spent in a given place: | |||
| $$ W\sim\Delta t $$ | |||
| In harmonic motion, the position of the light bulb is described by the expression | |||
| $$ x(t) = x_0 \sin\omega t $$ | |||
| From here, the speed value changes as | |||
| $$ v(t) = \dot{x}(t) =\omega \cdot x_0\cos \omega t $$ | |||
| The lower the speed, the more time it takes for the light bulb to cover equal intervals of time. | |||
| $$ v\sim\frac{1}{\Delta t} $$ | |||
| Thus, when the speed of the light bulb during harmonic motion is minimal, the energy perceived by the eye becomes greater. | |||
| $$ W\sim \frac{1}{v} $$ | |||
| Thus, the bulb appears brighter in places where its speed is minimal, i.e. at its extreme points. | |||
| </p> | |||
| <p style="text-align: right; font-style: italic; font-size: 14;"> | |||
| Aliaksandr Melnichenka<br> | |||
| </p> | |||
| <footer class="row container"> | |||
| <br> | |||
| <p> | |||
| <small> © <strong>Savchenko Solutions</strong>, 2023-2024 <br></small> | |||
| </p> | |||
| <p> | |||
| <small>All rights belong to the authors. <br> Commercial use of materials - with the written permission of the authors. <br> alex@savchenkosolutions.com <br></small> | |||
| </p> | |||
| </footer> | |||
| </body> | |||
| </html> | |||