Ch 19, Temperature

Homework Assignment:

Ch19: Questions 5, 8, *, 13, 14

Ch19: Problems 1, 4, 10, 19, 24, 26, 33, 45, 50

19.Q5: Why should the amalgam used in dental fillings have the same average coefficient of thermal expansion as a tooth? What would occur if they were mismatched?

19.Q8: Markings to indicate length are placed on a steel tape in a room that has a temperature of 22oC. Are measurements made with the tape on a day when the temperature is 27oC greater than, less than, or the same length as the object's length?

19.Q*: The pendulum of a certain pendulum clock is made of brass. When the temperature increases, does the clock run too fast, run too slowly, or remain unchanged?.

19.Q13. An automobile radiator is filled to the brim with water when the engine is cool. What happens to the water when the engine is running and the water is heated? What do modern automobiles have in their cooling systems to prevent the loss of coolants?

19.Q14: Metal lids on glass jars can often beloosened by running them under hot water. How is this possible?

19.1 Convert the following to equivalent temperaturs on the Celsius and Kelvin scales:

(a) the normal human body temperature, 98.6o F

(b) the air temperature on a cold day, - 5o F

19.4 There is a temperature whose numerical value is the same on both the Celsius and Fahrenheit scales. What is this temperature?

19.10 The concrete sections of a certain superhighway are designed to have a length of 25.0 m. The sections are poured and cured at 10.0oC. What minimum spacing should the engineer leave between the sections to eliminae buckling of the concrete is to reach a temperature of 50.0oC?

19.19 A concrete walk is poured on a day when the temperature is 20.0oC, in such a way that the ends are unable to move.

(a) What is the stress in the cement on a hot day of 50.0oC?

(b) Does the concrete fracture?

Take Young's modulus for concrete to be 7.00 x 109 N/m2 and the tensile strength to be 2.0 x 109 N/m2

19.24 At 20.0oC, an aluminum ring has an inner diameter of 5.000 0 cm and a brass rod has a diameter of 5.050 0 cm.

(a) To what temperature must the ring be heated so that it will just slip over the rod?

(b) To what common temperature must the two be heated so that the ring just slips over the rod? Would this latter process work?

19.26 A tank having a volume of 0.100 m3 contains helium gas at 150 atm. How many balloons can the tank blow up if each filled balloon is a sphere 0.300 m in diameter at an absolute pressure of 1.20 atm?

19.33 An automobile tire is inflated with air originally at 10.0oC and normat atmospheric pressure. During the process, the air is compressed to 28.0% of its original volum and its temperature is increased to 40.0oC.

(a) What is the tire pressure?

(b) After the car is driven at high speed, the tire air temperature rises to 85.0oC and the interior volume of the tire increases by 2.00%. What is the new (absolute)tire pressure in pascals?

19.45 A steel ball bearing is 4.00 cm in diameter at 20.0oC. A bronze plate has a hole in it that is 3.994 cm in diameter at 20.0oC. What common temperature must they have so that the ball just squeezes through the hole?

19.50 A cylinder is closed by a piston connected to a spring of constant 2.0 x 103 N/m. While the spring is relaxed, the cylinder is filled with 5.00 L of gas at a pressure of 1.00 atm and a temperature of 20.0oC.

(a) If the piston has a cross-sectional area of 0.010 0 m2 and a negligible mass, how high will it rise when the temperature is increased to 250oC?

(b) What is the pressure of the gas at 250oC? 



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