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| <span><img src="../../img/book.png"></span><span>Savchenko Solutions</span> | | <span><img src="../../img/book.png"></span><span>Savchenko Solutions</span> |
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| <p class="author"> | | <p class="author"> |
| Solutions of Savchenko Problems in Physics <br> | | Solutions of Savchenko Problems in Physics <br> |
| <i><b>knowledge must be free</b></i> | | <i><b>knowledge must be free</b></i> |
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| <h3 id="back-link"><a href="../../#2.1">$\leftarrow$Back</a></h3> | | <h3 id="back-link"><a href="../../#2.1">$\leftarrow$Back</a></h3> |
| | | |
| <h3> Statement </h3> | | <h3> Statement </h3> |
| <p> | | <p> |
| $2.1.42.$ Why is it easier to pull out a nail that is firmly embedded in a log if you simultaneously rotate it around its own axis when pulling it out? | | $2.1.42.$ Why is it easier to pull out a nail that is firmly embedded in a log if you simultaneously rotate it around its own axis when pulling it out? |
| </p> | | </p> |
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| <h3>Solution</h3> | | <h3>Solution</h3> |
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| <figcaption> | | <figcaption> |
| Forces acting on a driven nail | | Forces acting on a driven nail |
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| The sliding friction force acts along the line of motion in the opposite direction; its magnitude is determined only by the coefficient of friction of the surfaces (i.e. for a given nail it is conditionally constant in magnitude and does not depend on the method of motion). | | The sliding friction force acts along the line of motion in the opposite direction; its magnitude is determined only by the coefficient of friction of the surfaces (i.e. for a given nail it is conditionally constant in magnitude and does not depend on the method of motion). |
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