[DoctorBeaver (OP)]

A coil spring or the same spring under compression?

[dentstudent]

I think they have to weigh the same...there is no mass added or subtracted through compression - there is force added though, so if you have the spring on a set of bathroom scales, say, and push down, you would be measuring the additional downward force used by your hand to compress the spring as well as the weight of the spring itself, which is perhaps why it might look as though the spring weighs more. So, you'd be adding potential energy but no mass.

[DoctorBeaver (OP)]

Sorry, wrong answer.

[Bored chemist]

The coiled one by E=MC^2 but I chalenge you to demonstrate it.

[Seany]

Have fun outboffing everyone. []

[dentstudent]

Clearly, I'm not a physicist so I welcome a duffers guide,  but does this mean that energy has some sort of quantum mass? So the spring's weight changes by the increase in potential energy? Perhaps I'm guessing wildly and should leave it to the experts!

[DoctorBeaver (OP)]

Our splendid BoredChemist has the right answer.

A coiled spring has more potential energy than an uncoiled 1. Therefore, for E=MC^2 to remain balanced, the righthand side of the equation must reflect an increase also. C cannot increase so the only answer is for M to increase.

(OK, I suppose I should've asked "Which has the most mass?")

The same holds true for a given volume of cold water & the same volume of cold water (or for anything weighed at different temperatures).

So, ladies, when you look at the scales when you weigh yourselves and go "AAAARRRRGH!", simply immerse yourself in a bath of cold water & hey presto, you will weigh less!  []

[syhprum]

I take it that if I cut the bond holding it in a compressed state so that it oscillates then it would radiate gravitational waves (also hard to demonstrate).

[DoctorBeaver (OP)]

I take it that if I cut the bond holding it in a compressed state so that it oscillates then it would radiate gravitational waves (also hard to demonstrate).

erm... well... er... oh gosh, is that the time? I've got to go  [:I]

[Seany]

Where to? Beaverland? []

[lightarrow]

A coil spring or the same spring under compression?

Ok, now I ask you a question:
You compress a gas isothermically. Will it weigh more after compression?