Hysteresis in spring tension-extension graph Steps:

• Tension-extension graph for spring-mass shows loading (O to R) and unloading curves, with areas representing work and energy.
• Total work done by external force during extension equals area under loading curve (elastic PE stored plus dissipated).
• Energy recovered during unloading equals area under unloading curve.
• Difference (hysteresis loop area SQR) is irrecoverable energy lost to heat or deformation.

Why D is correct:

• Area SQR is the hysteresis loop, representing dissipated energy per Hooke's law extension with non-ideal behavior, which cannot be recovered as elastic potential.

Why the others are wrong:

• A: Area SPR includes part of loading curve but overstates recoverable energy, ignoring hysteresis losses.
• B: Area SPQ may approximate work against gravity (mgx), but loss of GPE is simply mgx, not tied to this specific area.
• C: Area SOR under loading curve includes both stored and lost energy, so not purely elastic potential.

Final answer: D