Springs are considered a non-conservative force why is the

[mrshappy0]

Homework Statement

Quick conceptual questions:

Is springs are considered a non-conservative force why is the mechanical energy conserved when a moving object compresses the spring?

Homework Equations

The Attempt at a Solution

This isn't a homework question or anything but I working on a problem that involves a spring and the problem says that a mass horizontally attached to a spring is moving compressed by a bullet being shot into the mass (wood) and that the mechanical energy is conserved during the compression of the spring. Confused.

 

[Doc Al]

Is springs are considered a non-conservative force why is the mechanical energy conserved when a moving object compresses the spring?

Who said that the spring force is non-conservative?

 

[mrshappy0]

Hmm... Wow.. People troll to much. hah.. So it is conservative.

 

[Doc Al]

Sure, a spring force is conservative. That's why you can have a spring potential energy function.

But be careful with that 'bullet getting shot into the wood' problem. While the spring compression is conservative, the initial collision of bullet and wood does not conserve kinetic energy: it's an inelastic collision.

 

[mrshappy0]

Right. Potential energy is conserved in inelastic collisions. This allows the use of the potential energy = kinetic energy. THanks Doc!

 

[Doc Al]

Potential energy is conserved in inelastic collisions. This allows the use of the potential energy = kinetic energy.

Not exactly! What's conserved in an inelastic collision (and all collisions, actually) is momentum.

 

[mrshappy0]

Oops I meant momentum. Slipped up on my words. To many new concepts flopping around in my word recall section in my brain.