GED Science TestPhysical ScienceMedium
A student is investigating how the period of a simple pendulum changes with its length. They measure the time for 20 oscillations for pendulums of various lengths. What is the dependent variable in this experiment?
- AThe length of the pendulum string
- BThe amplitude of the swing
- CThe time for 20 oscillations
- DThe mass of the pendulum bob
Show answer & explanationAnswer & explanation
Correct answer: C. The time for 20 oscillations
In an experiment, the dependent variable is the factor that is measured or observed and is expected to change in response to the independent variable. Here, the student is measuring 'the time for 20 oscillations' to see how it changes with length.
Why the other options are wrong
- A. The length of the pendulum string is the independent variable, as it is purposefully changed by the student.
- B. The amplitude of the swing is usually a controlled variable or another independent variable, not the measured outcome in this specific setup.
- D. The mass of the bob is typically kept constant or is an independent variable if its effect is being studied.
Dependent Variable
The variable in an experiment that is measured or observed and whose value depends on the changes made to the independent variable.
- The 'effect' or 'outcome' of the experiment.
- Plotted on the y-axis of a graph.
- Responds to changes in the independent variable.
Memory trick: Variables: Independent changes, dependent responds, controlled stays the same.