. The principles of physics. Fio. 52. Experiment 3.— Arrange some kind of rotating apparatus, R(Fig. 62). Suspend a skein of thread a (Fig. 53) by a string, and cause it to rotate; it assumes the shape ofthe oblate spheroid a. Mount a glassglobe G (Fig. 52) about one-tenthfull of colored water, and liquid gradually leaves the bot-tom, rises, and forms an equatorialring within the glass. This illustratesthe probable method by which theearth, on the supposition that it wasonce in a fluid state, assumed itspresent spheroidal state. (Explain.)Pass a string through the longest diame
. The principles of physics. Fio. 52. Experiment 3.— Arrange some kind of rotating apparatus, R(Fig. 62). Suspend a skein of thread a (Fig. 53) by a string, and cause it to rotate; it assumes the shape ofthe oblate spheroid a. Mount a glassglobe G (Fig. 52) about one-tenthfull of colored water, and liquid gradually leaves the bot-tom, rises, and forms an equatorialring within the glass. This illustratesthe probable method by which theearth, on the supposition that it wasonce in a fluid state, assumed itspresent spheroidal state. (Explain.)Pass a string through the longest diameter of an onion c, and causeit to rotate; the onion gradually changes its position so as to rotate onits shortest axis. It can be demonstrated mathematically, as well as experi-mentally, that a freely rotating body is in stable equilibrium. Fig. 53. THE PENDULUM. 77 only when rotating about its shortest diameter; hence thetendency of a rotating hody to take this position. 1. a. What Is the cause of the stretching force exerted on the rubbercord when you swing a return ball about your hand ? 6. Suppose thatyou double the velocity of the ball; how many times shall you increasethis stretching force ? 2. In what way can the tension in the string (Fig. 51) be so muchincreased as to break it ? 3. Why do wheels and grindstones, when rapidly rotating, tend tobreak, and the pieces to fly oft ? 4. On what does the magnitude of the pull between a rotating bodyand its center of motion depend ? 5. o. Explain the danger of a carriage being overturned in turning acorner. 6. How many fold is the tendency to overturn increased bydoubling the velocity of the carriage ? 6. Account for the curvilinear orbits of the planets. 7. How are their motions in their orbits and around their axes main-tained ? 8. In what way should the rails be laid s
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectphysics, bookyear1895
