A cylindrical enclosure is rotated rapidly and steadily about a horizontal axis. Molten metal is poured into the rotating cylindrical sheath and then cooled, forming the finished product. Turning the sheath at a high rotation rate forces the solidifying metal strongly to the outside. Any bubbles are displaced toward the axis, so unwanted voids will not be present in the casting. The guide at the factory challenges your group to solve the following problem in under a minute: Suppose a copper pipe of inner radius 1.33 cm and outer radius 1.49 cm is to be cast. To eliminate bubbles and give high structural integrity, the centripetal acceleration of each bit of metal should be at least 100g. What rotation rate, in revolutions per minute, is required? You are determined to be the first one to get the answer.

A cylindrical enclosure is rotated rapidly and steadily about a horizontal axis. Molten metal is poured into the rotating cylindrical sheath and then cooled, forming the finished product. Turning the sheath at a high rotation rate forces the solidifying metal strongly to the outside. Any bubbles are displaced toward the axis, so unwanted voids will not be present in the casting. The guide at the factory challenges your group to solve the following problem in under a minute: Suppose a copper pipe of inner radius 1.33 cm and outer radius 1.49 cm is to be cast. To eliminate bubbles and give high structural integrity, the centripetal acceleration of each bit of metal should be at least 100g. What rotation rate, in revolutions per minute, is required? You are determined to be the first one to get the answer.