Problem 222
Sphere Packing
What is the length of the shortest pipe, of internal radius 50mm, that can fully contain 21 balls of radii 30mm, 31mm, …, 50mm?
Give your answer in micrometres (10-6 m) rounded to the nearest integer.
球体打包
将21个半径分别为30mm、31mm、……、50mm的球完全装入一根内径50mm的管子，所需管长最短是多少？
将你的答案用微米(10-6 m)表示，并四舍五入到最近的整数。