The top surface of the passenger car of a train moving at a velocity of 70 km/h is 2.8 m wide and 8 m long. The top surface is absorbing solar radiation at a rate of 200 W/m², and the temperature of the ambient air is 30°C. Assuming the roof of the car to be perfectly insulated and the radiation heat ex- change with the surroundings to be small relative to convec- tion, determine the equilibrium temperature of the top surface of the car. Answer: 35.1°C

The top surface of the passenger car of a train moving at a velocity of 70 km/h is 2.8 m wide and 8 m long. The top surface is absorbing solar radiation at a rate of 200 W/m², and the temperature of the ambient air is 30°C. Assuming the roof of the car to be perfectly insulated and the radiation heat ex- change with the surroundings to be small relative to convec- tion, determine the equilibrium temperature of the top surface of the car. Answer: 35.1°C

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

See similar textbooks

Similar questions

Hi, can you help me to answer this question using the first law of thermodynamics formula to explain this event? On a hot summer day, a student turns his fan on when he leaves his room in themorning. When he returns in the evening will the room be warmer or cooler than theneighborouing rooms ? Explain your answer using the first law of thermodynamics.Assume ALL doors and windows are kept closed.
An electric room heater (radiator) element is 25 cm long and 4 cm in diameter. The element dissipates heat to the surroundings at 1500 W mainly by radiation, the surrounding temperature being 15°C. Determine the equilibrium temperature of the element surface in Rankine.
Solar radiation is incident on the glass cover of asolar collector at a rate of 700 W/m2. The glass transmits88 percent of the incident radiation and has an emissivityof 0.90. The entire hot water needs of a family in summercan be met by two collectors 1.2 m high and 1 m wide. Thetwo collectors are attached to each other on one side so thatthey appear like a single collector 1.2 m * 2 m in size. Thetemperature of the glass cover is measured to be 35°C on aday when the surrounding air temperature is 25°C and thewind is blowing at 30 km/h. The effective sky temperaturefor radiation exchange between the glass cover and the opensky is 240°C. Water enters the tubes attached to the absorberplate at a rate of 1 kg/min. Assuming the back surface of theabsorber plate to be heavily insulated and the only heat lossto occur through the glass cover, determine (a) the total rateof heat loss from the collector, (b) the collector efficiency,which is the ratio of the amount of heat transferred to…
The boiling temperature of nitrogen at atmosphericpressure at sea level (1 atm) is -196°C. Therefore, nitrogenis commonly used in low-temperature scientific studies sincethe temperature of liquid nitrogen in a tank open to the atmosphereremains constant at -196°C until the liquid nitrogen inthe tank is depleted. Any heat transfer to the tank results inthe evaporation of some liquid nitrogen, which has a heatof vaporization of 198 kJ/kg and a density of 810 kg/m3 at1 atm.Consider a 4-m-diameter spherical tank initially filledwith liquid nitrogen at 1 atm and -196°C. The tank isexposed to 20°C ambient air with a heat transfer coefficientof 25 W/m2·K. The temperature of the thin-shelled sphericaltank is observed to be almost the same as the temperatureof the nitrogen inside. Disregarding any radiation heatexchange, determine the rate of evaporation of the liquidnitrogen in the tank as a result of the heat transfer from theambient air.
An 8-m-internal-diameter spherical tank made of 1.5-cm-thick stainless steelAISI 302 is used to store iced water at 0°C. The tank is located in a roomwith temperature 25°C. The outer surface of the tank is black (emissivity, ε= 1), the heat transfer between the outer surface of the tank and thesurroundings is by natural convection and radiation. The convection heattransfer coefficients at the inner and the outer surfaces of the tank are 80W/m2K and 10W/m2K, respectively; and the outer surface temperature of thetank is 5°C. Draw the equivalent thermal circuit of the system. Determine the total heat transfer rate to the iced water in the tank and the total amount of ice at 0°C that melts after 24 hours.
Fill in the blanks: An electric room heater (radiator) element is 25 cm long and 4 cm in diameter. The element dissipates heat to the surroundings at 1500 W mainly by radiation, the surrounding temperature being 15°C. Determine the equilibrium temperature of the element surface in Rankine.
Hi, can you help me to answer this question using the first law of thermodynamics? On a hot summer day a student turns his fan on when he leaves his room in themorning. When he returns in the evening will the room be warmer or cooler than theneighborouing rooms ? Explain your answer using the first law of thermodynamics.Assume ALL doors and windows are kept closed.
Q2/ A 4-m-internal-diameter spherical tank made of 1.75-cm-thick stainless steel (k 15 W/m °C) is used to store iced water at 0°C. The tank is located in a room whose temperature is 35°C. The walls of the room are also at 35°C. The outer surface of the tank is black, and heat transfer between the outer surface of the tank and the surroundings is by natural convection and radiation. The convection heat transfer coefficients at the inner and the outer surfaces of the tank are 80 W/m2 °C and 10 W/m2· °C, respectively. Determine (a) the rate of heat transfer to the iced water in the tank and (b) the amount of ice at 0°C that melts during a l-h period. The heat of fusion of water at atmospheric pressure is hif 334 kJ/kg.
Awatermelon initially at 35°C is to be caoled by dropping itinto a lake at 15°C. After 4 h and 40 min of cooling the center temperature of watermelon is measured to be 20°C. Treating the watermelon 25 a 20-c-diameter sphere and using the properties k = 0.618 Wim
A window is made up of two panes of glass (with surface temperatures of 15 oCand 5 oC) that are separated by a gap of 3 cm. The said window has a height of2 m and a width of 5 m. Initially, the gap is filled with air (flowing via temperaturegradient). Then, this air space is partially evacuated such that the pressure isalready 0.1 mpa. This is done to lessen the heat transfer between the two panes ofglass. Both glass surfaces have an emissivity of 0.9. Calculate the rate of heattransfer (W) through the panes.
The top surface of the passenger car of a train moving at a velocity of 115 km/h is 2.8 m wide and 8 m long. The top surface is absorbing solar radiation at a rate of 380 W/m2 and the temperature of the ambient air is 30°C. Assuming the roof of the car to be perfectly insulated and the radiation heat exchange with the surroundings to be small relative to convection, determine the equilibrium temperature of the top surface of the car. The properties of air at 30°C are (Table A-15) k = 0.02588 W/m⋅°C, v = 1.608 × 10−5 m2/s, and Pr = 0.7282.The equilibrium temperature of the top surface of the car is:
QI/The top surface of the passenger car of a train moving at a velocity of 70 km/h is 2.8 m wide and 8 m long. The top surface is absorbing solar radiation at a rate of 200 W/m2, and the temperature of the ambient air is 30°C. Assuming the roof of the car to be perfectly insulated and the radiation heat exchange with the surroundings to be small relative to convection, determine the equilibrium temperature of the top surface of the car. Ans =35.1 c