# Spring Stretch Length

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Spring stretch length, abbreviated as $$l_s$$, is the length by which a spring extends or stretches when a force is applied to it.  This can be described by Hooke's law, which relates the force applied to a spring to its extension.

### Spring Stretch Length Considerations

• Elastic Limit  -  This calculation assumes that the spring is within its elastic limit, meaning it returns to its original length when the force is removed.  If the spring is stretched beyond its elastic limit, it will not obey Hooke's law, and permanent deformation may occur.
• Initial Length  -  The stretch length is the change in length from the spring's natural (unstressed) length.  If you need the total extended length of the spring, you would add this stretch length to the spring's initial (unloaded) length.
• Multiple Forces  -  If multiple forces are applied, or if the spring is part of a system with multiple springs, the net force and resulting stretch may need to be calculated considering all forces and constraints involved.

Understanding these principles and the context of the applied force, you can accurately determine how much a spring will stretch under a given load.

### Spring stretch length formula

$$l_s = \sqrt{ 2 \; PE_s \;/\; k_s }$$
Symbol English Metric
$$l_s$$ = spring stretch length $$in$$  $$mm$$
$$PE_s$$ = spring potential energy $$lbf-ft$$  $$J$$
$$k_s$$ = spring force constant $$lbf$$ $$N$$

Tags: Spring Length