What kind of simple machine is a ruler?

A ruler is not typically considered a simple machine, as it does not fit into the traditional categories of simple machines such as levers, pulleys, or inclined planes. However, a ruler can be used in conjunction with other simple machines to measure and mark distances, which can aid in the application of mechanical principles. In this sense, a ruler can be seen as a tool that complements the function of simple machines rather than being classified as one itself.