# Is an extended spring gain mass from potential energy? [duplicate]

Is it true that when a spring is extended, potential energy is stored in spring and result in gain of mass of the spring?

Yes, spring mass will increase but in very very small amount.

As per Mass energy equivalence the amount of mass gain will be(E=mc2):

m= E/C2

for example if spring have store 1 Joule of potential energy when it is extended then the increased mass will be:

m =1/299792458= 3.33564095198152e-9

• i think its not proper to calculate changes in the mass of a body in a field or in a system having potential energy...otherwise our mass will change if we go to top floor of my apartment! – drvrm Jun 3 '16 at 6:09
• @drvrm Please check en.wikipedia.org/wiki/Mass%E2%80%93energy_equivalence read strict mass–energy equivalence , yes it will change our mass. – editinit Jun 3 '16 at 8:21
• @ editinit .. i think you are correct .. in the limiting cases of very small changes in the mass of a system .. one can visualize it. – drvrm Jun 3 '16 at 11:53