The graph in the figure shows the force on an object as a function of the elongation caused by that force. Which statement about this object is true?
A) The object obeys Hooke's law at all points from A to C.
B) The object obeys Hooke's law at all points from B to C.
C) The object obeys Hooke's law at all points from A to B.
D) The elastic limit occurs at point C.
E) The region of elastic behavior occurs from B to C.

Question

The graph in the figure shows the force on an object as a function of the elongation caused by that force. Which statement about this object is true? 
A) The object obeys Hooke's law at all points from A to C. 
B) The object obeys Hooke's law at all points from B to C. 
C) The object obeys Hooke's law at all points from A to B. 
D) The elastic limit occurs at point C. 
E) The region of elastic behavior occurs from B to C.

Quizplus · Accepted Answer

Hooke's law states that the force on an object is directly proportional to the object's elongation. Therefore, for an object to obey Hooke's law, its force versus elongation graph must be a straight line passing through the origin. The graph in the figure is a straight line passing through the origin from point A to point B, indicating that the object obeys Hooke's law in this region. However, beyond point B, the graph starts to curve, indicating that the object is no longer obeying Hooke's law. Therefore, the best choice is C, which states that the object obeys Hooke's law at all points from A to B.

The Graph in the Figure Shows the Force on an Object