How to identify a tape measure? Please speak more carefully and understand better. Thank you. It is urgent.

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.

principle

The tape measure can be rolled up because it has a spring. When measuring the length, the length of the ruler and the spring is actually lengthened. Once the measurement is completed, the spring in the tape measure will automatically shrink, and the ruler will also shrink under the action of the spring force, so the tape measure will be rolled up.

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.

scale

Tape measure and tape measure have the same metric scale, and one centimeter tape measure is equal to one centimeter tape measure, except Mongolian tape measure used by black-hearted clothing merchants;

The reverse side of the tape measure is the city scale: city scale, city inch; The front of the tape measure is divided into two parts, one is metric scale (meters, centimeters) and the other is English scale (feet, inches).

The number on the tape measure

The numbers on the tape measure are divided into two rows, one row is CM /CM, the other row is inch, 1CM is about 0.3937 inch, and 1 inch is about =2.54CM, so the shorter number unit between the two numbers is cm, the longer number unit is inch, and the number font in cm is smaller than inch,1.

metering method

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The tape head is loose, so that we can measure the size. There are two ways to measure dimensions with a tape measure. One is hanging on the object, and the other is propping on the object. The difference between these two methods lies in the thickness of the iron sheet at the head of the tape measure. The function of loosening the tape head is to compensate the iron sheet at the tape head when the tape head abuts against the object.

The power of tape measure

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There is a small piece of steel in the "inner core" of the tape measure, which acts as a spring. You can also think of it this way, that is, the small steel wire on the trigger of the toy pistol is used to "hit" the bullet. When it is pulled out, it is forced to bend, and after it is released, the external force (refers to the force of hand pulling, but the friction force is less than the elastic force of small steel wire) disappears, so it automatically rebounds.

Moreover, there is a folded part in front of the tape measure, which works at this time, so that the tape measure is stuck outside and will not be completely retracted.

At first, it was loose, but after pulling it out, it became tight. There should be a recovery process after letting go, so it will bounce back automatically.

At first, it was loose inside, but it was tight when it was pulled, and there was elasticity in the middle. If it is loose, it will naturally bounce back.