Where's the energy come from?

[claerwen]

Among the Christmas knick-knack gift items there are numerous examples of levitating globes, pens, tops, etc.<br /><br />Obviously they are suspended by magnets, but why do they stay suspended? A constant force must be applied to keep them in the air - requiring a constant expenditure of energy. <br /><br />Where does this energy come from? The magnets don't deplete (do they?)

 

[vogon13]

What holds a steel beam together on a bridge?<br /><br />Same thing.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[vogon13]

{that was probably too concise, but I'm sure I will be revised and extended by the truth squad.}<br /><br /><img src="/images/icons/wink.gif" /><br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[harmonicaman]

How right you are, <b>Vogon!</b><br /><br />...and I'm sure they'll be right along here any moment now...<br /><br />But in the meantime, here's a nice webpage with instructions on how to build your own electromagnetic levitating devices at home - enjoy:<br /><br />http://my.execpc.com/~rhoadley/magsusp.htm

 

[bbrock]

Energy is work/time. Work is force applied over a distance. If an object is suspended motionless, is energy actually being expended. <br /><br />If you stand motionless in one spot, is energy being applied to hold you in that spot?? Actually, no. Regardless of the mechanism. Your weight is countered by the earth pushing you up -- no net acceleration. A toy ball suspended in a magnetic field. Same thing. <br />