In the laboratory, a stick 1 m long is pivoted at various points to illustrate the motion of a physical pendulum. A plot of the period versus the distance of the pivot point from the center of mass is shown. The data presented demonstrate which of the following?
A) The motion of a pendulum is circular about the center of mass.
B) The center of mass is at 0.4 m.
C) The graph is meaningless in this form.
D) There is a minimum period in the neighborhood of 1.5 s at a pivotal distance of approximately 0.4 m from the center of mass.
E) The graph should be drawn as a straight line from A to C; point D is obviously wrong.

Question

In the laboratory, a stick 1 m long is pivoted at various points to illustrate the motion of a physical pendulum. A plot of the period versus the distance of the pivot point from the center of mass is shown. The data presented demonstrate which of the following? 
A) The motion of a pendulum is circular about the center of mass. 
B) The center of mass is at 0.4 m. 
C) The graph is meaningless in this form. 
D) There is a minimum period in the neighborhood of 1.5 s at a pivotal distance of approximately 0.4 m from the center of mass. 
E) The graph should be drawn as a straight line from A to C; point D is obviously wrong.

Quizplus · Accepted Answer

The plot shows a minimum period in the neighborhood of 1.5 s at a pivotal distance of approximately 0.4 m from the center of mass. This indicates that the motion of a physical pendulum depends on the pivotal distance from the center of mass and that there is a point at which the period of oscillation is minimized. Therefore, choice D is the correct answer.  Choices A, B, and E are incorrect since they are not supported by the information given in the plot. Choice C is also incorrect since the plot provides meaningful information about the motion of a physical pendulum.

In the Laboratory, a Stick 1 M Long Is Pivoted