The volume of a 2-meter-long steel cylinder is calculated by increasing its surface area by 16 square decimeters

The area of the bottom section increased by 4
Bottom area: 16 △ 4 = 4 (square decimeter)
2 m = 20 decimeters
Volume: 4 × 20 = 80 (cubic decimeter)

The surface area of a 1-meter-long steel cylinder is reduced by 25.12 square decimeters after a 2-decimeter section is cut off

Bottom perimeter: 25.12 △ 2 = 12.56 decimeters
Bottom radius: 12.56 △ 3.14 △ 2 = 2cm
Bottom area: 3.14 × 2 & # 178; = 12.56 square decimeters
Surface area: 12.56 × (1 × 10 + 2) = 150.72 square decimeters
Volume: 12.56 × (1 × 10) = 125.6 cubic decimeter

After two 2-meter-long cylinders with the same bottom area are assembled into a cylinder steel, the surface area is reduced by 0.6 square decimeter. If each cubic decimeter of steel weighs 7.8 kg, how many kg does the assembled steel weigh?

Bottom area: 0.6 △ 2 = 0.3 (square decimeter) 2 m = 20 decimeter volume of cylinder: 0.3 × 20 × 2 = 12 (cubic decimeter) weight: 2 × 7.8 = 93.6 (kg) answer: the weight of the steel after assembly is 93.6 kg

After two 2-meter-long cylinders with the same bottom area are assembled into a cylinder steel, the surface area is reduced by 0.6 square decimeter. If each cubic decimeter of steel weighs 7.8 kg, how many kg does the assembled steel weigh?

When two cylinder steels with equal bottom area are welded into a cylinder, the surface area is reduced by 0.6 square decimeter
If each cubic decimeter of steel weighs 7.8 grams, how many kilograms does the steel weigh after welding?

The reduced part of the surface area is the area of the two bottom surfaces 0.6 △ 2 = 0.3 (square decimeter), which is the bottom area of the cylinder
And then it's divided into 2 meters = 20 decimeters, 0.3 × 20 = 6 cubic decimeters, which is the volume of the cylinder
6 × 7.8 = 46.8 (g) = 0.0468 kg
Look at the questions carefully, especially the unit. How do I feel that you have made a mistake about the unit

Cut the 2-meter-high cylindrical steel into two sections, and the surface area will be increased by 25.12 square decimeters. What is the surface area of this cylindrical steel?
It's better to write down the formula

Cylindrical steel cross-section into two sections, the surface area increased by two bottom areas
2 bottom area = 25.12
Bottom area = 12.56
Radius = 2 decimeters
The surface area of this cylindrical steel
=2 bottom area + side area
=25.12+3.14*2*2*20
=276.32 (square decimeter)

A steel cylinder is 2m long. After it is cut into two small cylinders, the surface area increases by 25.12 square decimeters. What is the original volume of this steel

25.12 / 2 = 12.56 (square decimeter)
2 m = 20 decimeters
12.56 times 20 = 251.2 (cubic decimeter)

There is a 2-meter-long cylindrical steel. If it is cut into three identical cylinders, the surface area will increase by 40 square centimeters. What is the volume of this cylinder______ Cubic centimeter

2 m = 200 cm, 40 △ [(3-1) × 2] × 200 = 40 △ [2 × 2] × 200, = 40 △ 4 × 200, = 2000 (cubic cm); answer: the volume of this cylinder is 2000 cubic cm. So the answer is: 2000

Cylinder volume formula?
Who knows

Perimeter of rectangle = (length + width) × 2 perimeter of square = side length × 4 area of rectangle = length × width area of square = side length × side length area of triangle = bottom × height △ 2 area of parallelogram = bottom × height area of trapezoid = (upper bottom + lower bottom) × height △ 2 diameter = radius × 2 radius = straight diameter △ 2 area of circle

Cylinder volume formula
I have a corn building with a diameter of 2.93 meters and a height of 2.50 meters. How many cubic meters is it? Who knows?

V = s bottom × height
S bottom = Π × R ^ 2 = Π × d ^ 2 / 2 = Π * 2.93 ^ 2 / 4 = 6.739
V = s bottom × height = 6.739 * 2.50 = 16.85m3

The volume of a 2-meter-long steel cylinder is calculated by increasing its surface area by 16 square decimeters