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Usually Small Rotating: It seemed re-imarkable to think of a star rotating around its paxis once every 1.337 sec, but one could cal-ulate that even much faster rotation would be erfectly possible. It remained to be seen what enomenon on such a rapidly rotating star auld send out a continuous radio beam that mould sweep over the earth once in each rota-like a rotating lighthouse beacon. Almost ertainly what appeared to man to be fan-stically dense states of matter would be in-Dived. Man had thus been once more reminded he shared the universe with objects about hich he knew very little.
In rough machine grinding, swinging-frame grinding machines are used to bring a rotating abrasive wheel in contact with a workpiece to remove gates and risers from foundry castings or excess material from forgings. Thin, strong cutoff wheels are used to cut metal billets, bars, and plates to rough size. usually small rotating workpieces may be grinding, or grinding with the flat surface of a
moved against rotating grinding wheels. Diskng with the flat rotating abrasive disk, is suited to cleaning up large flat surfaces. Portable grinders permit the operator to guide the path of the grinding wheel to areas of the workpiece that would otherwise be inaccessible.
The modern theory of rifling has evolved from the work of these early designers. Modern projectiles are constructed with one or more rotating bands of soft metal, slightly larger in diameter than the bore of the gun. As the projectile moves down the bore under the action of the propellant gases, the lands (areas between grooves) cut through the rotating band, engraving it to conform to the cross section of the bore and causing rotation of the projectile. The ribs of metal from the rotating band, by projecting into the grooves, prevent the escape of gas past the projectile. The |
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