Final answer:
Measuring a 3x5 card's fall due to gravity may present difficulties due to variables like mass and gravitational pull, impacting the outcome of an experiment on the acceleration of falling objects. These difficulties illustrate the concept of uncertainty in measurement and the importance of measurement tool precision.
Step-by-step explanation:
The difficulty in measuring the 3x5 card in the given context is not explicitly defined, though it may relate to an experiment that involves gravity and mass. If the measurement difficulties were to connect to Part B, which discusses mass and gravitational force, it could be that the challenge lies in accurately measuring how different masses are influenced by gravitational pull during a free-fall experiment. In such a setup, the masses used (whether it's light like a piece of paper or heavy like a textbook) and the consistent force of gravity could affect the outcome in unexpected ways, demonstrating that heavier objects do not necessarily fall faster than lighter ones, contradicting a common misconception.
Regarding the review questions, uncertainty in measurements refers to the inevitable small range of error that exists when taking any measurement due to limitations in measurement tools or human precision. Rulers with finer graduations are typically more reliable for measuring because they provide more detail and reduce the chance of reading errors. To make the top ruler more accurate, one could ensure it has the smallest possible graduations, is made from a material that doesn't easily warp, and is used in a consistent manner.