Answer
See explanation
Work Step by Step
(a) The variability in the measurements could be due to several factors such as:
Instrumental errors: The measuring devices used by the students might not be calibrated correctly, which can lead to systematic errors. For example, if the ruler used by the students is slightly bent or has a zero offset, it can affect all measurements in the same way, leading to a systematic error.
Personal errors: Each student may have a different technique for measuring the length of the metal bar, such as the angle at which they hold the ruler, or how they align it with the end of the bar. These differences can lead to random errors, as each student's measurement will be influenced by their own personal technique.
Given that the measurements vary by a small amount, it is likely that the errors are random, as systematic errors would have caused the measurements to be shifted in the same direction.
(b) The students' measurements are different from the day before because the teacher informed them that the bars had contracted due to being in the refrigerator. This suggestion created a bias in the students' minds, leading them to expect the measurements to be smaller, which likely affected their measurements. This illustrates the importance of controlling for bias in scientific experiments, as any preconceived ideas or suggestions can influence the outcome of the experiment. In this case, the temperature difference was too small to have any measurable effect on the length of the bars, and the students' measurements were likely influenced by their expectation rather than the actual length of the bars.
