Experiment with heated stretched springs.

[Low-Q]

I have a spring made of steel. The spring is stretched out, and kept in that position. There is now potential energy in the stretched spring due to tension. If I heat the spring up to 700 degrees celsius, the tension in the stretched spring disappear, and when the springs cools down it is permanently stretched, and I must apply energy to compress it into initial shape.

Where did the potential energy in the stretched spring go? Did I destroy energy or what happened?

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[gsal]

do you know where the springness of a spring comes from, in the first place?

it has to do with the fact that it is a solid and the fixed position of its molecules.

when you stretch the spring and heat it up to a certain temperature...you are basically 'melting' it a bit and putting heat into the system to allow molecules to re-position (re-distant) themselves, release stresses and settle on a new position of minimum potential energy.

you may want to read up on metallurgical processes like annealing.

and yes, 700 degrees is just about the annealing temperature for steel.

 

[Low-Q]

do you know where the springness of a spring comes from, in the first place?

it has to do with the fact that it is a solid and the fixed position of its molecules.

when you stretch the spring and heat it up to a certain temperature...you are basically 'melting' it a bit and putting heat into the system to allow molecules to re-position (re-distant) themselves, release stresses and settle on a new position of minimum potential energy.

you may want to read up on metallurgical processes like annealing.

and yes, 700 degrees is just about the annealing temperature for steel.

Does this mean that the metal will release its tension as heat? Say I use 1J to stretch the spring, then the spring release 1J of heat when I heat it up?

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[sophiecentaur]

Yep.