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free/or 0.5$ |
| 55843 | An automobile tire is inflated with air originally at 10.0°C and normal atmospheric pressure. During the process, the air is compressed to 28.0% of its original volume and the temperature is increased to 40.0°C. (a) What is the tire pressure? (b) After the car is driven at high speed, the tire air temperature rises to 85.0°C and the interior volume of the tire increases by 2.00%. What is the new tire pressure (absolute) in pascals? |
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| 55844 | An automobile radiator is filled to the brim with water while 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? |
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| 55845 | An auditorium has dimensions 10.0 m X 20.0 m X 30.0 m. How many molecules of air fill the auditorium at 20.0°C and a pressure of 101 kPa? |
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| 55846 | An athlete whose mass is 70.0 kg drinks 16 oz (453.6 g) of refrigerated water. The water is at a temperature of 35.0°F.
(a) Ignoring the temperature change of the body that results from the water intake (so that the body is regarded as a reservoir always at 98.6°F), find the entropy increase of the entire system.
(b) What If? Assume that the entire body is cooled by the drink and that the average specific heat of a person is equal to the specific heat of liquid water. Ignoring any other energy transfers by heat and any metabolic energy release, find the athlete’s temperature after she drinks the cold water, given an initial body temperature of 98.6°F. Under these assumptions, what is the entropy increase of the entire system? Compare this result with the one you obtained in part (a). |
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| 55847 | At what temperature would the average speed of helium atoms equal?
(a) The escape speed from Earth, 1.12 X 104 m/s and
(b) The escape speed from the Moon, 2.37 X 103 m/s? (See Chapter 13 for a discussion of escape speed, and note that the mass of a helium atom is 6.64 X 10-27 kg.) |
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| 55848 | At a pressure of 1 atm, liquid helium boils at 4.20 K. The latent heat of vaporization is 20.5 kJ/kg. Determine the entropy change (per kilogram) of the helium resulting from vaporization |
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| 55849 | At point A in a Carnot cycle, 2.34 mol of a monatomic ideal gas has a pressure of 1 400 kPa, a volume of 10.0 L, and a temperature of 720 K. It expands isothermally to point B, and then expands adiabatically to point C where its volume is 24.0 L. An isothermal compression brings it to point D, where its volume is 15.0 L. An adiabatic process returns the gas to point A. (a) Determine all the unknown pressures, volumes and temperatures as you fill in the following table: |
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| 55850 | At NASA’s John H. Glenn research center in Cleveland, Ohio, free-fall research is performed by dropping experiment packages from the top of an evacuated shaft 145 m high. Free fall imitates the so-called micro gravity environment of a satellite in orbit.
(a) What is the maximum time interval for free fall if an experiment package were to fall the entire 145 m?
(b) Actual NASA specifications allow for a 5.18-s drop time interval. How far do the packages drop and
(c) What is their speed at 5.18 s?
(d) What constant acceleration would be required to stop an experiment package in the distance remaining in the shaft after its 5.18-s fall |
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| 55851 | At high noon, the Sun delivers 1 000 W to each square meter of a blacktop road. If the hot asphalt loses energy only by radiation, what is its equilibrium temperature? |
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| 55852 | At 25.0 m below the surface of the sea (p =1 025 kg/m3), where the temperature is 5.00°C, a diver exhales an air bubble having a volume of 1.00 cm3. If the surface temperature of the sea is 20.0°C, what is the volume of the bubble just before it breaks the surface? |
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| 55853 | At 20.0°C, 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) If only the ring is heated, what temperature must it reach so that it will just slip over the rod? (b) What If? If both are heated together, what temperature must they both reach so that the ring just slips over the rod? Would this latter process work? |
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| 55854 | Assuming that the force acting on a 2-g bullet, as it passes horizontally through the barrel of a rifle, varies with time in the manner shown, determine the maximum net force To, applied to the bullet when it is fired. The muzzle velocity is 500 m/s when t = 0.75 ms. Neglect friction between the bullet and the rifle barrel. |
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| 55855 | Assume that the Earth’s atmosphere has a uniform temperature of 20°C and uniform composition, with an effective molar mass of 28.9 g/mol.
(a) Show that the number density of molecules depends on height according to nv(y) = nOe –mgy/kBT Where n0 is the number density at sea level, where y = 0. This result is called the law of atmospheres.
(b) Commercial jetliners typically cruise at an altitude of 11.0 km. Find the ratio of the atmospheric density there to the density at sea level. |
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| 55856 | Assume that a hailstone at 0°C falls through air at a uniform temperature of 0°C and lands on a sidewalk also at this temperature. From what initial height must the hailstone fall in order to entirely melt on impact? |
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| 55857 | As a 1.00-mol sample of a monatomic ideal gas expands adiabatically, the work done on it is - 2 500 J. The initial temperature and pressure of the gas are 500 K and 3.60 atm. Calculate
(a) The final temperature and
(b) The final pressure. You may use the result of Problem 53 |
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| 55858 | Argon gas at atmospheric pressure and 20.0°C is confined in a 1.00-m3 vessel. The effective hard-sphere diameter of the argon atom is 3.10 X 10-10 m. (a) Determine the mean free path . (b) Find the pressure when = 1.00 m. (c) Find the pressure when = 3.10 X 10-10 m |
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| 55859 | Argon enters a turbine at a rate of 80.0 kg/min, a temperature of 800°C and a pressure of 1.50 MPa. It expands adiabatically as it pushes on the turbine blades and exits at pressure 300 kPa.
(a) Calculate its temperature at exit.
(b) Calculate the (maximum) power output of the turning turbine.
(c) The turbine is one component of a model closed-cycle gas turbine engine. Calculate the maximum efficiency of the engine. |
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| 55860 | An aluminum rod 0.500 m in length and with a cross-sectional area of 2.50 cm2 is inserted into a thermally insulated vessel containing liquid helium at 4.20 K. The rod is initially at 300 K.
(a) If half of the rod is inserted into the helium, how many liters of helium boil off by the time the inserted half cools to 4.20 K? (Assume the upper half does not yet cool)
(b) If the upper end of the rod is maintained at 300 K, what is the approximate boil-off rate of liquid helium after the lower half has reached 4.20 K? (Aluminum has thermal conductivity of 31.0 J/s cm K at 4.2 K; ignore its temperature variation. Aluminum has a specific heat of 0.210 cal/g °C and density of 2.70 g/cm3. The density of liquid helium is 0.125 g/cm3) |
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| 55861 | An aluminum pipe, 0.655 m long at 20.0°C and open at both ends, is used as a flute. The pipe is cooled to a low temperature but then is filled with air at 20.0°C as soon as you start to play it. After that, by how much does its fundamental frequency change as the metal rises in temperature from 5.00°C to 20.0°C? |
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| 55862 | An aluminum cup of mass 200 g contains 800 g of water in thermal equilibrium at 80.0°C. The combination of cup and water is cooled uniformly so that the temperature decreases by 1.50°C per minute. At what rate is energy being removed by heat? Express your answer in watts |
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