582_Physics ProblemsTechnical Physics

582_Physics ProblemsTechnical Physics - 584 P20.19 Heat and...

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584 Heat and the First Law of Thermodynamics P20.19 Qmc Tm L == Cu Cu N vap N 2 2 ej 100 293 773 480 0414 .. . . kg 0.092 0 cal g C C cal g kg ⋅° ° = = bg af m m *P20.20 The original gravitational energy of the hailstone-Earth system changes entirely into additional internal energy in the hailstone, to produce its phase change. No temperature change occurs, either in the hailstone, in the air, or in sidewalk. Then mgy mL y L g = ×⋅ F H G I K J 333 10 98 1 1 340 10 5 4 . . . Jkg ±ms kg m s J m 2 22 P20.21 (a) Since the heat required to melt 250 g of ice at 0°C exceeds the heat required to cool 600 g of water from 18°C to 0°C, the final temperature of the system (water + ice) must be 0 ° C. (b) Let m represent the mass of ice that melts before the system reaches equilibrium at 0°C. QQ mL m c T m m fw w i cold hot C ±Jkg ±kg ±Jkg C C C g, so the ice remaining g g g =− ° − ×= ° ° ° = 0 3 33 10 0 600 4186 0 18 0
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This note was uploaded on 12/14/2011 for the course PHY 203 taught by Professor Staff during the Fall '11 term at Indiana State University .

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