Final answer:
An inside micrometer is the correct tool to use to precisely measure the diameter inside a cylinder. While rulers can measure lengths and simple dimensions, inside micrometers provide the precision needed for internal measurements of cylinders.
Step-by-step explanation:
To precisely measure the diameter inside a cylinder, an inside micrometer should be held squarely across the cylinder. Rulers may provide measurements for objects like the length of a crayon, but for the specific task of measuring the internal diameter of a cylinder accurately, inside micrometers are designed to fit within the cylinder and provide a precise measurement, which can be read to a high degree of accuracy, often to the nearest thousandth of an inch or hundredth of a millimeter. On the other hand, outside micrometers are used to measure the outside dimensions of objects, and dial indicators are used to measure small amounts of movement, such as in a machining process.
When we consider measurement precision, instruments like rulers can vary depending on the unit and smallest graduation. For example, a ruler with millimeter markings can measure more precisely than a ruler with only centimeter markings, as the former allows for a more refined estimate of the measurement. Furthermore, measuring volumes in liquid-filled graduated cylinders requires readings at the bottom of the meniscus to account for the curvature of the liquid's surface, which stands as a testament to the importance of correct procedures and appropriate tools for different measurement scenarios.