A cone has a diameter of 8 cm and a volume of () cubic cm

A cone has a diameter of 8 cm and a volume of () cubic cm


4^2×3.14×15/3=251.2



The length of a steel pipe is 200 cm, the outer diameter is 12 cm, and the inner diameter is 8 cm. 1 cubic cm steel pipe weighs 7.8 g. how many kg does 50 such steel pipes weigh?


Inner radius: 8 △ 2 = 4 (CM), outer radius: 12 △ 2 = 6 (CM), bottom area of steel pipe: 3.14 × 62-3.14 × 42, = 3.14 × 20, = 62.8 (square cm); volume of steel pipe: 62.8 × 200 = 12560 (cubic cm); weight of 50 steel pipes: 12560 × 7.8 × 50, = 4898400 (g)