Question

Evaluate You are asked to study the effect of temperature on the volume of a balloon. The balloon’s size increases as it is warmed. What is the independent variable? The dependent variable? What factor is held constant? How would you construct a control?

Short answer

In this experiment, the independent variable is the temperature, and the dependent variable is the volume of the balloon. The factor held constant is the pressure and type of gas inside the balloon. To construct a control, use a balloon with the same type of gas in an environment with constant temperature for comparison.

Step-by-step solution

Identify the Independent Variable

An independent variable is the variable that we manipulate in an experiment to determine its effect on another variable. In this case, we are studying the effect of temperature on the volume of a balloon. So, the independent variable is the temperature.

Identify the Dependent Variable

A dependent variable is the variable that we measure in an experiment, which is affected by the independent variable. In this situation, we are measuring the change in the volume of a balloon due to the change in temperature. Therefore, the dependent variable is the volume of the balloon.

Identify the Factor held Constant

The factor held constant is the variable that does not change during the experiment, ensuring that the results are not affected by any external factors. In this case, the factors that we would want to keep constant include the pressure and the type of gas inside the balloon. We can assume that the pressure inside the balloon remains constant during the experiment, as well as the type of gas.

Constructing a Control

A control is a group or condition in an experiment that remains unchanged to serve as a comparison to the experimental group. To construct a control in this experiment, we can use a balloon with the same type of gas and placed in an environment where the temperature remains constant. By comparing the change in the volume of the balloons exposed to different temperatures with the control balloon, we can determine the effect of temperature on the volume of a balloon.

Key concepts

Independent Variable

In scientific experiments, the independent variable is the main factor you purposely change to observe its impact on another factor. When studying the effect of temperature on the volume of a balloon, temperature is the independent variable. You deliberately alter the temperature to see how it affects the balloon's volume.

It's crucial to only adjust one independent variable at a time to ensure clear and accurate results. This careful control allows researchers to establish a direct cause-and-effect relationship between the independent and dependent variables.

• Single change: Only change temperature in this experiment.
• Controlled outcome: Observes its specific impact on another variable.

Dependent Variable

The dependent variable is what you measure in an experiment. It changes in response to the independent variable being modified. In the case of the balloon experiment, the volume of the balloon is the dependent variable. As the temperature changes, you measure how the balloon's volume is affected.

Accurate measurement of the dependent variable is essential for gathering reliable data. This variable reflects the results of your experiment, showing how the changes in independent variable affect the system you are studying.

• Measurement: Volume of the balloon.
• Response observation: Changes with temperature variations.

Control Variables

Control variables are factors that are kept constant throughout an experiment to ensure a fair test. These variables could inadvertently affect the dependent variable if they change, creating confounding results. In the balloon experiment, factors like pressure inside the balloon and the type of gas should remain unchanged.

By controlling these other variables, you make certain that the results are only due to the change in the independent variable. This step is critical for validating your experimental results.

• Constant conditions: Ensures reliability of results.
• Examples: Pressure and type of gas in the balloon.

Scientific Method

The scientific method is a structured approach to investigate and understand phenomena. It involves a series of steps that help ensure that your findings are reliable and valid. When applying this method to the balloon experiment, you'll follow these steps:

1. **Observation:** Noticing that the balloon changes size with temperature changes.
2. **Hypothesis:** Formulating an assumption like "If the temperature increases, then the volume of the balloon will also increase."
3. **Experiment:** Manipulating temperature (independent variable) and measuring the balloon's volume (dependent variable).
4. **Analysis:** Comparing the data collected to determine if the hypothesis holds true.

By following the scientific method, you minimize bias and ensure that your experimental conclusions are based on evidence. It's a fundamental process for conducting credible and logical scientific research.