Hysteresis loss in rubber cord

Steps:

• The stretching curve shows work done on the cord, equal to the area under it.
• The contraction curve shows work done by the cord, equal to the area under it.
• The shaded area between curves is the difference in these areas.
• This difference represents energy dissipated as heat due to internal friction in rubber.

Why B is correct:

• In hysteresis, the loop area quantifies dissipated energy from viscoelastic damping, per the definition of mechanical hysteresis.

Why the others are wrong:

• A: Stored elastic potential energy is the area under the stretching curve alone.
• C: Work done on the cord during stretching is the full area under the stretching curve.
• D: Work done by the cord during contraction is the full area under the contraction curve.

Final answer: B