What is the tape measure prepared by primary school?

Normal household tape measure, but maybe younger students like to use it, which is sold in general stationery stores.

Tape measure is a common measuring tool in daily life. What we often see is a steel tape measure, which is often used in construction and decoration, and is also one of the necessary tools for families. Divided into fiber tape measure, tape measure, waist measure and so on. Lu Banchi, Feng Shui ruler and secretary also belong to steel tape measure.

trait

First, the tape measure will not fail if it is too deformed. Why not fail; The clockwork in the tape measure is very long, and the interval between its complete relaxation and complete contraction is very large, including the whole stroke of the tape measure, and there are margins at both ends, so the tape measure will not fail.

Second, pulling one meter long and pulling two meters long makes no difference; The spring of the tape measure is very thin, and the deformation is very small when it is tightened, so the reaction force is very small, and you can't feel the change of force when you stretch the ruler.