The cross section of a steel pipe is annular, the radius of the inner circle is 5cm, the radius of the outer circle is 8cm, what is the cross section area of the steel pipe

The cross section of a steel pipe is annular, the radius of the inner circle is 5cm, the radius of the outer circle is 8cm, what is the cross section area of the steel pipe

S circle = π R
π8��-π5��=39π
If π is 3.14
The result was 122.46

What method can be used to measure the diameter or cross-sectional area of a metal wire more accurately?

If it is a thick single core wire, use micrometer, vernier caliper and other tools to measure the diameter
If it is a multi-core wire, it can be considered to measure the volume first, and then divide it by the length to get the cross-sectional area. The multi-core wire often has insulating skin, so it is necessary to remove the insulating skin and then measure the volume. The drainage method or the load-bearing method can be used to measure the volume. The drainage method needs a better measuring cylinder, and the weighing method needs to know the density

How to measure the cross sectional area of power line

The diameter of a single core wire is directly measured with a micrometer or caliper, and then the radius is calculated. According to the circle area formula = π R & # 178; = 3.14 * r & # 178; it can be calculated. If it is multi stranded, the area of a single wire needs to be calculated first, and then multiplied by the number of wires

What method can be used to measure the diameter or cross-sectional area of a metal wire more accurately with a scale?

Put the conductor against the wall, erect to measure the length, lay flat to measure the diameter, calculate the cross-sectional area through the cross-sectional area formula, and pay attention to multiple measurements to calculate the average value