A sample of an alloy wire is stretched by an increasing force F F\,F until its extension reaches 4.5 mm (point PPP), after which it is fully unloaded. The force-extension graph for this loading and unloading cycle is shown below.
Which option correctly states the permanent extension of the wire and the elastic strain energy recovered by the wire during the unloading phase?
Permanent extension =1.5 mm= 1.5\text{ mm}=1.5 mm; elastic strain energy recovered =1.80 J= 1.80\text{ J}=1.80 J
Permanent extension =3.0 mm= 3.0\text{ mm}=3.0 mm; elastic strain energy recovered =0.90 J= 0.90\text{ J}=0.90 J
Permanent extension =1.5 mm= 1.5\text{ mm}=1.5 mm; elastic strain energy recovered =0.90 J= 0.90\text{ J}=0.90 J
Permanent extension =3.0 mm= 3.0\text{ mm}=3.0 mm; elastic strain energy recovered =1.35 J= 1.35\text{ J}=1.35 J