Passage IV
One type of torsion pendulum consists of a wire tied to a rod with a disk on each end. The pendulum is suspended from a support (see Figure 1).
The rod is turned, twisting the wire, and then released, causing the rod and disks to oscillate (twist back and forth) in a horizontal arc, as shown in the top views in Figure 2.
The period is the time required for the rod to complete 1 round trip. Tables 1-3 give the periods of torsion pendulums made with identical wires and various disk masses, rod masses, and rod lengths.
19. To obtain the data in Tables 1-3, the experimenter directly controlled all but which of the following variables?
Your Answer is
Correct Answer is D
Explanation
In the three experiments, the period is a dependent variable, that is to say, the period is not a parameter artificially set by the experimenter, but the result of the experiment, so the period is not directly controlled by the experimenter.