The tape can be rolled up because the tape is equipped with a spring. When the measuring length is pulled out, the length of the ruler and the spring is actually extended. Once the measurement is completed, the spring in the tape will automatically shrink, and the ruler will follow the force of the spring. Shrink so the tape measure rolls up.
First, the tape is too deformed to fail. Why didn't it fail? The mainspring in the tape measure is very long, and it's completely relaxed to a completely tight range. The entire stroke of the tape measure includes it, leaving a margin on both ends, so the tape measure will not fail.
Second, pulling one meter long and pulling two meters long, there is no difference in pulling force; the mainspring of the tape measure is very thin, and the amount of deformation when shrinking is small, so the reaction force is small, and no change in force is felt when the ruler is pulled.
The metric scale of the tape measure and the tape measure are the same. One centimeter of the tape measure is equal to one centimeter of the tape measure, except for the blindfold tape used by the black-hearted clothing merchant;
The opposite side of the tape measure is the city scale: the city scale, the city inch; the front of the tape measure is divided into two parts, one side is the metric scale (meter, centimeter), and the other is the inch scale (foot, inch).
Numbers on a tape measure
The numbers on the tape measure are divided into two rows. One row is in centimeters / CM and one row is in inches. 1CM is about 0.3937 inches and 1 inch is about 2.54CM. So the shorter number unit is centimeters. The longer is inches, and the number font in units of centimeters is also smaller than the inches, 100 centimeters = 1 meter. Generally, the units are centimeters in use.