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| + | <!DOCTYPE html> | ||
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| + | </head> | ||
| + | <body style=""> | ||
| + | <header style="text-align:center;"> | ||
| + | <h2>Solutions of Savchenko Physics Textbook</h2> | ||
| + | <p class="author"> | ||
| + | Aliaksandr Melnichenka <br/> | ||
| + | October 2023 | ||
| + | </p> | ||
| + | </header> | ||
| + | |||
| + | <h3 id="back-link"><a href="../#1.1">$\leftarrow$Back</a></h3> | ||
| + | |||
| + | <h3> Statement </h3> | ||
| + | <p> | ||
| + | $1.1.23^*.$ The shooter tries to hit a disk of radius $R$, which moves from one wall to another at constant modulo velocity so fast that it cannot be tracked. Draw a graph of the probability of hitting the disk as a function of the distance between the aiming point and the left wall. | ||
| + | </p> | ||
| + | <center> | ||
| + | <figure> | ||
| + | <img src="statement.png" | ||
| + | loading="lazy" width="230" /> | ||
| + | <figcaption> | ||
| + | For problem $1.1.23^*$ | ||
| + | </figcaption> | ||
| + | </figure> | ||
| + | </center> | ||
| + | <p> | ||
| + | The shots are fired at height $R$ from the floor perpendicular to the direction of motion of the disc. At what point is the least and most probable shot? What is their value? Consider the cases $L > 4R$, $4R > L > 2R$, where $L$ is the distance between the walls. | ||
| + | </p> | ||
| + | |||
| + | <h3>Solution</h3> | ||
| + | <p> | ||
| + | |||
| + | <center> | ||
| + | <figure> | ||
| + | <img src="animation.gif" alt="1.1.23" | ||
| + | loading="lazy" width="300" /> | ||
| + | <figcaption> | ||
| + | Wheels moving | ||
| + | </figcaption> | ||
| + | </figure> | ||
| + | </center> | ||
| + | |||
| + | <p> | ||
| + | When the target is moving, a bystander is less likely to see the target from the edge, as it stays there for a shorter period of time. | ||
| + | </p> | ||
| + | <p> | ||
| + | Thus, the maximum probability will be observed on the interval: | ||
| + | </p> | ||
| + | <p style="text-align: center;"> | ||
| + | $$\left\{\begin{matrix} | ||
| + | 0 \leq x < 2R\\ | ||
| + | L-2R < x \leq L | ||
| + | \end{matrix}\right.$$ | ||
| + | </p> | ||
| + | <p> | ||
| + | Since the velocity of the target is constant, and finding the target in the range $2R \leq x \leq L-2R$ is equally likely, the probability of finding it in this range is equal to the ratio of the diameter to the length of this range: $\frac{2R}{L-2R}$. | ||
| + | </p> | ||
| + | <p> | ||
| + | Graphs corresponding to these modes: | ||
| + | </p> | ||
| + | |||
| + | <center> | ||
| + | <figure> | ||
| + | <img id="sol" src="sol.png" alt="1.1.23" | ||
| + | loading="lazy" width="350" /> | ||
| + | <figcaption> | ||
| + | Probability of a hit as a function of aiming distance | ||
| + | </figcaption> | ||
| + | </figure> | ||
| + | </center> | ||
| + | </p> | ||
| + | |||
| + | <h4>Answer</h4> | ||
| + | <p> | ||
| + | <a href="#sol">See Fig.</a> Zero at the walls. The largest at any place at a distance from the walls, | ||
| + | greater than $2R$, and equal to $2R/(L-2R)$ at $L > 4R$; at any place at a distance from the walls greater than $L - 2R$, and equal to one at $4R > L > 2R$. | ||
| + | </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> astrosander01@gmail.com <br></small> | ||
| + | </p> | ||
| + | </footer> | ||
| + | </body> | ||
| + | |||
| + | </html> | ||
| @@ -0,0 +1,123 @@ | |||
| <!DOCTYPE html> | |||
| <html lang="en"> | |||
| <head> | |||
| <meta charset="utf-8"> | |||
| <meta name="viewport" content="width=device-width, initial-scale=1.0"> | |||
| <meta http-equiv="content-language" content="en"> | |||
| <meta name="keywords" content="solutions, savchenko, physics problems, olympiad physics, physics book"> | |||
| <meta name="description" content="A website with solutions to physics problems from Savchenko Textbook"> | |||
| <meta property="og:title" content="Savchenko Solutions"> | |||
| <meta property="og:image" content="img/logo.png"> | |||
| <meta property="og:description" content="A website with solutions to physics problems from Savchenko Textbook"> | |||
| <meta name="yandex-verification" content="6cfda41f74038368"> | |||
| <title>Savchenko Solutions</title> | |||
| <link rel="stylesheet" href="https://savchenko-physics.github.io/css/css-latex/style.css"> | |||
| <link rel="icon" href="https://savchenko-physics.github.io/img/logo.png" type="image/png"> | |||
| <script src="https://savchenko-physics.github.io/js/jquery-1.10.1.min.js"></script> | |||
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| <script type="text/x-mathjax-config"> | |||
| MathJax.Hub.Config({ | |||
| extensions: ['tex2jax.js'], | |||
| jax: ['input/TeX', 'output/HTML-CSS'], | |||
| tex2jax: { | |||
| inlineMath: [['$', '$'], ['$', '$']], | |||
| processEscapes: true, | |||
| processClass: 'tex2jax', | |||
| ignoreClass: 'html' | |||
| }, | |||
| showProcessingMessages: false, | |||
| messageStyle: 'none' | |||
| }); | |||
| </script> | |||
| </head> | |||
| <body style=""> | |||
| <header style="text-align:center;"> | |||
| <h2>Solutions of Savchenko Physics Textbook</h2> | |||
| <p class="author"> | |||
| Aliaksandr Melnichenka <br/> | |||
| October 2023 | |||
| </p> | |||
| </header> | |||
| <h3 id="back-link"><a href="../#1.1">$\leftarrow$Back</a></h3> | |||
| <h3> Statement </h3> | |||
| <p> | |||
| $1.1.23^*.$ The shooter tries to hit a disk of radius $R$, which moves from one wall to another at constant modulo velocity so fast that it cannot be tracked. Draw a graph of the probability of hitting the disk as a function of the distance between the aiming point and the left wall. | |||
| </p> | |||
| <center> | |||
| <figure> | |||
| <img src="statement.png" | |||
| loading="lazy" width="230" /> | |||
| <figcaption> | |||
| For problem $1.1.23^*$ | |||
| </figcaption> | |||
| </figure> | |||
| </center> | |||
| <p> | |||
| The shots are fired at height $R$ from the floor perpendicular to the direction of motion of the disc. At what point is the least and most probable shot? What is their value? Consider the cases $L > 4R$, $4R > L > 2R$, where $L$ is the distance between the walls. | |||
| </p> | |||
| <h3>Solution</h3> | |||
| <p> | |||
| <center> | |||
| <figure> | |||
| <img src="animation.gif" alt="1.1.23" | |||
| loading="lazy" width="300" /> | |||
| <figcaption> | |||
| Wheels moving | |||
| </figcaption> | |||
| </figure> | |||
| </center> | |||
| <p> | |||
| When the target is moving, a bystander is less likely to see the target from the edge, as it stays there for a shorter period of time. | |||
| </p> | |||
| <p> | |||
| Thus, the maximum probability will be observed on the interval: | |||
| </p> | |||
| <p style="text-align: center;"> | |||
| $$\left\{\begin{matrix} | |||
| 0 \leq x < 2R\\ | |||
| L-2R < x \leq L | |||
| \end{matrix}\right.$$ | |||
| </p> | |||
| <p> | |||
| Since the velocity of the target is constant, and finding the target in the range $2R \leq x \leq L-2R$ is equally likely, the probability of finding it in this range is equal to the ratio of the diameter to the length of this range: $\frac{2R}{L-2R}$. | |||
| </p> | |||
| <p> | |||
| Graphs corresponding to these modes: | |||
| </p> | |||
| <center> | |||
| <figure> | |||
| <img id="sol" src="sol.png" alt="1.1.23" | |||
| loading="lazy" width="350" /> | |||
| <figcaption> | |||
| Probability of a hit as a function of aiming distance | |||
| </figcaption> | |||
| </figure> | |||
| </center> | |||
| </p> | |||
| <h4>Answer</h4> | |||
| <p> | |||
| <a href="#sol">See Fig.</a> Zero at the walls. The largest at any place at a distance from the walls, | |||
| greater than $2R$, and equal to $2R/(L-2R)$ at $L > 4R$; at any place at a distance from the walls greater than $L - 2R$, and equal to one at $4R > L > 2R$. | |||
| </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> astrosander01@gmail.com <br></small> | |||
| </p> | |||
| </footer> | |||
| </body> | |||
| </html> | |||