Effect on the weight of a bird in a closed cage with a spring attached to it - Physics Stack Exchange most recent 30 from physics.stackexchange.com 2019-09-23T09:12:59Z https://physics.stackexchange.com/feeds/question/481711 https://creativecommons.org/licenses/by-sa/4.0/rdf https://physics.stackexchange.com/q/481711 0 Effect on the weight of a bird in a closed cage with a spring attached to it Ishi https://physics.stackexchange.com/users/228398 2019-05-22T19:14:13Z 2019-06-09T11:39:29Z <p>I have read the question in which the difference in the weight of a bird in a closed and a open system is described. </p> <p>But what happens if there is a closed cage with wires and also a spring attached to that system?</p> <p>In my notebook, it is written that:</p> <blockquote> <p>in this system, the weight of the bird will be same as that of the bird in an open cage.</p> </blockquote> <p>I don't understand this at all. Please help me with this.</p> https://physics.stackexchange.com/questions/481711/-/483412#483412 0 Answer by César González for Effect on the weight of a bird in a closed cage with a spring attached to it César González https://physics.stackexchange.com/users/233340 2019-05-30T21:54:54Z 2019-05-30T21:54:54Z <p>The weight of an object is the force with wihch the earth pulls it down, that is <span class="math-container">$W=mg$</span> where <span class="math-container">$m$</span> is its mass and <span class="math-container">$g$</span> the acceleration of gravity. So, the weight of a bird does not depend on it's enclosure. </p> https://physics.stackexchange.com/questions/481711/-/483641#483641 3 Answer by João Bravo for Effect on the weight of a bird in a closed cage with a spring attached to it João Bravo https://physics.stackexchange.com/users/202416 2019-06-01T05:34:33Z 2019-06-09T11:39:29Z <p>The <strong>weight</strong> of the bird is given by <span class="math-container">$\vec W = m \cdot \vec g$</span>, with m being its mass and <span class="math-container">$\vec g$</span> the acceleration of gravity. The only visible dependency here is on gravity. It does not depend on any other force!</p> <p>You can interpret the weight of an object simply as a force acting on it. </p> <ol> <li><p>The bird can be standing in a <strong><em>cage on the ground</em></strong>, in which case its weight would be counteracted by the force exerted upwards by the cage floor.</p></li> <li><p>The bird can be standing in a <strong><em>free-falling cage</em></strong>, in which case its weight would not be counteracted by any force. It would feel <em>weightless</em>, but it is in fact its weight that is accelerating it down.</p></li> <li><p>The bird can be standing in a <strong><em>cage attached by a spring to a roof</em></strong>, in which case its weight would still be counteracted by the force exerted upwards by the cage floor. The spring can stretch due to the mass it is suspending, but that does not change this fact. Even if you make the cage bounce with the spring, what changes is the force exerted by the cage floor on the bird, not the bird's weight.</p></li> </ol> <blockquote> <p>In a given system with a defined acceleration constant, the weight of an object with constant mass is constant.</p> </blockquote>