Why Does a Spring Return to Its Original Position After Being Stretched?

[tellmesomething]

Consider a spring in its natural length. I start pulling the string and the force i apply increase from 0 to 5, while this happens theres a restoring force wanting to be back in its original position(intermolecular force) and i am able to stretch the string until this spring force or restoring force equals to my applied force. Now when i remove my hand why does it go back to its original position, i understand the reaction force is opposite in direction to my applied force and at the point where the extension stops the net force on the string is 0. But when i remove my hand does the external force vanish? Its still there right shouldnt the spring still be in equilibrium?

 

[Dale]

Your hand is the source of the applied force. Why would the applied force remain after its source leaves?

 

[tellmesomething]

Your hand is the source of the applied force. Why would the applied force remain after its source leaves?

when i push an object on a frictionless surface i dont remain in contact i merely give it a push and it continues moving until hit by an obstacle. can it not be similar to this?

 

[Dale]

when i push an object on a frictionless surface i dont remain in contact i merely give it a push and it continues moving

It doesn’t require a force to move in a straight line at a constant speed. That is Newton’s 1st law. When you stop pushing then the force stops in this case too.

 

[Lnewqban]

Consider a spring in its natural length. I start pulling the string and the force i apply increase from 0 to 5, while this happens theres a restoring force wanting to be back in its original position(intermolecular force) and i am able to stretch the string until this spring force or restoring force equals to my applied force.

The force that you apply deforms the crystals that form the metal.
The reactive force is directly proportional to that deformation, which is elastic (until certain point).

Now when i remove my hand why does it go back to its original position, i understand the reaction force is opposite in direction to my applied force and at the point where the extension stops the net force on the string is 0.

When you remove your hand, the force that was deforming the metal disappears, and the crystals naturally go back to the original position.

But when i remove my hand does the external force vanish? Its still there right shouldnt the spring still be in equilibrium?

Yes, the external force suddenly disappears, which breaks the previous equilibrium of hand-elastic forces.
The elastic force makes the spring return to its original length, while its magnitude goes from 5 to 0.