A cylindrical steel pipe, the inner diameter is 4, the wall thickness is 2 cm, the length is 2 m, and the weight of each cubic decimeter of steel is 7.8 kg How many kilos does it weigh? (4cm, wrong type) This is the supplementary condition

A cylindrical steel pipe, the inner diameter is 4, the wall thickness is 2 cm, the length is 2 m, and the weight of each cubic decimeter of steel is 7.8 kg How many kilos does it weigh? (4cm, wrong type) This is the supplementary condition

First of all, the unified unit is decimeter
If the inner diameter of the steel pipe is 4cm = 0.4 decimeter, the inner radius is 0.4 △ 2 = 0.2 decimeter,
If the outer diameter of steel pipe is 4 + 2 × 2 = 8 cm = 0.8 decimeter, then the outer radius is 0.8 △ 2 = 0.4 decimeter
Steel pipe length 2m = 20 decimeters
Volume of steel pipe = outer volume inner volume
=3.14×0.4×0.4×20-3.14×0.2×0.2×20
=3.14×3.2-3.14×0.8
=536 cubic decimeter
Steel pipe weight = 7.536 × 7.8 = 58.7808