Final answer:
The unit for the caterpillar's speed is centimeters per minute (cm/min). A graph to represent this data would have Time (min) on the x-axis and Speed (cm/min) on the y-axis. A ruler is the best tool to measure the length of a caterpillar.
Step-by-step explanation:
To determine the unit of a caterpillar's speed when the distance is measured in centimeters (cm) and time in minutes (min), you simply need to divide the distance by time, getting the unit centimeters per minute (cm/min). When graphing the data, the correct setup would place Time (min) on the x-axis and Speed (cm/min) on the y-axis. Time is considered the independent variable because it is the variable that you control or that precedes the other, while speed is the dependent variable as it depends on the time taken.
The appropriate tool for measuring the length of a caterpillar is a ruler, which provides the precision needed for such small measurements. In composing a graph, both axes should be clearly labeled with the name of each variable and the units in parentheses. Scales should be chosen such that all the data can be comfortably plotted. For instance, for the time intervals taken every 10 minutes, the x-axis can be numbered from 0 to 70 minutes with a tick mark every 10 minutes to reflect the measurements.