The topic here is stretching a rubber band. Figure 1 plots force against extension while the band is loaded and then unloaded.
Use Figure 1 to decide if the band is elastic or plastic, and whether it follows Hooke's law.
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The band is elastic, because when the force is taken off, the unloading curve comes back to the origin, so the band returns to its original length. Hooke's law needs force proportional to extension, which is a straight line through the origin, and both curves bend, so it is not obeyed. That is the first option. The two options that say Hooke's law is obeyed fail because the curves are not straight. The two plastic options fail because plastic deformation would leave the band permanently stretched, with some extension left at zero force. The loop shows that loading and unloading differ, but the band still ends at the origin.
How the marks are earned
- Choose elastic deformation with Hooke's law not obeyed: both curves return to zero extension, and neither is a straight line through the origin.
- One answer only: two answers earn nothing, and a circled or underlined right option counts if the box is blank.