The outlines of physics: an elementary text-book . mford, who was employedin the supervision of such work by the king of Bavaria,to the conception that heat was a mode of motion and wasproduced by the expenditure of work. Energy expendedin resistance to motion, in friction, is nearly alwaysentirely converted into heat. The following experiment,due to Tyndall, illustrates this transfer of energy, togetherwith the reverse process of converting heat energy intoenergy of motion: 169. Experiment 46.—Production of Steam directly from theHeat of Friction (Tyndalls Experiment). Apparatus : (i) A
The outlines of physics: an elementary text-book . mford, who was employedin the supervision of such work by the king of Bavaria,to the conception that heat was a mode of motion and wasproduced by the expenditure of work. Energy expendedin resistance to motion, in friction, is nearly alwaysentirely converted into heat. The following experiment,due to Tyndall, illustrates this transfer of energy, togetherwith the reverse process of converting heat energy intoenergy of motion: 169. Experiment 46.—Production of Steam directly from theHeat of Friction (Tyndalls Experiment). Apparatus : (i) A whirling table upon which is mounted a brass tube about2 cm. in diameter and about 10 cm. Ipng. (See Fig. 158.) (2) A cork whichfits the open end ofthe tube, and a wood-en clamp of the formshown in the :(a) The tube ispartly fiUed withwater, and the upperend is firmly closed by means of the cork. (b) The whirling table is put into motion, the tube being held inthe jaws of the clamp with sufficient pressure to produce as large an. Fig. 156. BELATIONS BETWEEN HEAT AND WOBK 189 amount of friction as can be obtained without causing the belt toslip. After driving the tube rapidly for a few minutes, a sufficientamount of heat will be developed to cause the water to boil. Steamwill be produced, and the pressure will rise until the cork is blownfrom the mouth of the tube. Here we have the transfer of the energyof motion, through the agency of friction, into heat energy. Theresult is a rise of temperature, together with a change of state fromthe liquid to the. gaseous form. The energy of motion of the cork isfar from being the equivalent of the energy of the work done in driv-ing the whirling table, because a large portion of the heat energyevolved is transferred to surrounding bodies, producing molecularmotions in them and rise of temperature. 170. Changes of Temperature as the Result of Compressionand Expansion. — One of the many ways in which energymay be stored i
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