Final answer:
To improve the accuracy and validity of her experiment, Cathy should randomly select cups, use consistent temperature measurement, control for environmental factors, and repeat the experiment multiple times. Each step plays a critical role in ensuring reliable and valid data regarding the thermal and expansion properties of the materials tested.
Step-by-step explanation:
To increase the accuracy and validity of Cathy's results in her experiment to investigate how well cups made of different materials maintain the temperature of a cold drink, several steps can be taken. These steps include:
- Randomly selecting cups from different materials for each trial to eliminate selection bias.
- Using a consistent temperature measurement method to ensure reliability in temperature readings.
- Controlling for environmental factors like room temperature to prevent external influences on the results.
- Repeating the experiment multiple times and calculating the average results to minimize the impact of outliers and increase statistical significance.
All of these measures are vital to ensuring that the data collected from the experiment is reliable and to accurately assess the thermal properties and expansion properties of each material under study. Importantly, each experiment should be designed safely, without extreme temperatures, to avoid risk and damage to the materials. An appropriate material for measuring temperature should be selected based on its accuracy over the specific range of temperatures anticipated during the study. This is crucial because the specific heat of each material will affect its capacity to maintain the temperature of the drink.