Very quick question about elastic potential energy?

[scilearner]

 

Now when the spring recoils, it loses its elastic potential energy to the dart. If it loses its energy how does it come back to its original shape. I'm thinking it is the elastic potential energy that is used to make the coil come back to its orginal shape.

 

Also let's say a spring was compressed and I took my hand away. Now it recoiled back to its shape. The spring didn't transfer any of its added elastic potential energy, to any other object. So does the spring has more energy now.

 

When I compress a spring I'm thinking I'm adding extra potential energy. Am I adding extra energy or, changing the allready existing energy in the spring to elastic potential energy.

 

Please excuse anyof my misunderstandings.

 

Thank you

Edited May 30, 2010 by scilearner

[swansont]

The original shape is the minimum-energy configuration, where there is no force. It's similar to a ball rolling downhill and coming to rest at the bottom; there is energy stored in the compressed spring, and you have to do work on the system to put it in that configuration. It won't happen spontaneously.

[scilearner]

The original shape is the minimum-energy configuration, where there is no force. It's similar to a ball rolling downhill and coming to rest at the bottom; there is energy stored in the compressed spring, and you have to do work on the system to put it in that configuration. It won't happen spontaneously.

 

Thanks for the reply swansont:-) So if there is a spring attached to the wall and I compress it and take my handaway. The spring recoils, now where is extra elastic potential converted to or given. Do the air molecules get the extra elastic potential energy. Or sometimes does the spring if not attached to a wall, jump up due to extra energy.

[Sisyphus]

Thanks for the reply swansont:-) So if there is a spring attached to the wall and I compress it and take my handaway. The spring recoils, now where is extra elastic potential converted to or given. Do the air molecules get the extra elastic potential energy. Or sometimes does the spring if not attached to a wall, jump up due to extra energy.

 

The spring will have kinetic energy. An ideal spring, once you release it, will oscillate endlessly between compressed->expanding->stretched->contracting, while the total energy (elastic potential energy + kinetic energy) remains constant. That is, its moving fastest at the slack position, and stops completely at the most compressed and most expanded positions before reversing direction.

 

A real spring, on the other hand, will lose energy to heat, to moving the air, etc., and will eventually come to rest in the slack position.

 

And if it's not attached it would jump, yes. An expanding spring would exert a force on the wall.

[scilearner]

The spring will have kinetic energy. An ideal spring, once you release it, will oscillate endlessly between compressed->expanding->stretched->contracting, while the total energy (elastic potential energy + kinetic energy) remains constant. That is, its moving fastest at the slack position, and stops completely at the most compressed and most expanded positions before reversing direction.

 

A real spring, on the other hand, will lose energy to heat, to moving the air, etc., and will eventually come to rest in the slack position.

 

And if it's not attached it would jump, yes. An expanding spring would exert a force on the wall.

 

Thanks Sisphysus. You answered the question very well.

 

I think so whenever you compress something like a spring, it comes back to its orginal shape giving a force, and if you get hit by it, you can use its elastic energy to do work on the hit object.