SpecialProblems5-70 - 1000 W/m 2 = 0.3 SP7: The energy...

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Special Problems for ME 200 - Spring 2011 Problems Due on January 28, 2011 SP5: At 20°C ethanol has a surface tension of 22.3 mN/m. Suppose that a film of ethanol is maintained on the wire as shown, one side of which can be moved. The original dimensions of the wire frame are as shown. Determine the work done (consider the film to be the system), when the wire is moved 10 mm in the direction indicated and b=20 mm and x=30 mm.
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SP6: Answer the following: a) Would a steel or aluminum flagpole freeze a tongue to it faster? Why? b) The outer surface of a satellite in space has an emissivity of 0.8 and an absorptivity of 0.3 for solar radiation. If solar radiation is incident on the spacecraft at a rate of 1000 W/m2, determine the surface temperature of the spacecraft when the radiation emitted equals the solar energy absorbed.
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Unformatted text preview: 1000 W/m 2 = 0.3 SP7: The energy required by animals to sustain life is derived from oxidation of ingested food. It is in essence burned in the body. A food sample is placed into a bomb type calorimeter with oxygen to measure the energy content of the food (see Fig. 2.16 in the text). Surrounding the vessel of food and oxygen is a water bath. The igniter ignites the food and oxygen mixture. This releases energy that heats the water, causing its temperature to rise. The power input to a stirrer used to circulate the water is 0.04 kW. In a 20-minute period the heat transfer from the bomb is 1200 kJ and the heat transfer from the water tank to the surrounding air is 60 kJ. Assuming no evaporation of water, determine the increase in the internal energy of the water....
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SpecialProblems5-70 - 1000 W/m 2 = 0.3 SP7: The energy...

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