A 100-kg person is working out in the gym dissipating 100 W of energy. How long would it take for their body temperature to rise by 1oC, ignoring all other forms of heat transfer in and out of their body? The specific heat of human tissue is 3.75 kJ kg-1 K-1. What is unreasonable about this calculation?
A 100-kg person is working out in the gym dissipating 100 W of energy. How long...
A resistor, part of a circuit, is dissipating at 0.1 W. It is shaped like a cylinder with a radius of 1.8 mm and a length of 1 cm. If the air in the cabinet is at 308 K and the resistor has a heat transfer coefficient of h = 13 W/m2K for natural convection and hrad of 6.5 W/m2K, what is the resistor’s temperature? Assume heat is lost by only convection and radiation in a parallel circuit. Now if...
While running, a 74 kg student generates thermal energy at a rate of 1300 W. To maintain a constant body temperature of 37.0 ∘C, this energy must be removed by perspiration or other mechanisms. Part A If these mechanisms failed and the heat could not flow out of the student's body, for what amount of time could a student run before irreversible body damage occurred? (Protein structures in the body are damaged irreversibly if the body temperature rises to 44.0...
While running, a 78 kg student generates thermal energy at a rate of 1100 W . To maintain a constant body temperature of 40 ∘C, this energy must be removed by perspiration or other mechanisms. If these mechanisms failed and the heat could not flow out of the student's body, for what amount of time could a student run before irreversible body damage occurred? (Protein structures in the body are damaged irreversibly if the body temperature rises to 44 ∘C...
While running, a 76 kg student generates thermal energy at a rate of 1100 W . To maintain a constant body temperature of 36 ∘C, this energy must be removed by perspiration or other mechanisms. If these mechanisms failed and the heat could not flow out of the student's body, for what amount of time could a student run before irreversible body damage occurred? (Protein structures in the body are damaged irreversibly if the body temperature rises to 44 ∘C...
How much time (in seconds) is needed for a surgical cauterizer to raise the temperature of 3.00 g of tissue from 37.0 degrees C to 100 degrees C ad then boil away 0.200 g of water, if it puts out 3.50 mA at 20.0 kV? Ignore heat transfer to the surroundings. (Assume the specific heat of tissue is 3,500 J/(kg*degreeC) and the latnet heat of vaporization of water is 2,256 kJ/kg.)
A piston-cylinder assembly initially contains 0.8 kg of air at 100 kPa and 300 K. It is then compressed in a polytropic process PV3 = C to half the original volume. Assuming the ideal gas model for air and specific heat ratio is constant, k=1.4, determine (a) the final temperature, (b) work and heat transfer, each in kJ. R= 0.287 kJ/kg K. W, 82
A silver sphere (k = 429 W/m.°C.p = 10,500 kg/m", Cp=0.235 kJ/kg-°C) is initially at 0°C. The sphere diameter is 5 cm. Now the sphere is exposed to ambient air at 40°C on all of its surfaces with a heat transfer coefficient of 12 W/ m K. Determine approximately how long it will take for the temperature of sphere to rise to 25°C. Ot=80 min t=28 min O t = 120 min o t= 18 min
Radiation of Energy The rate of heat transfer by emitted radiation is determined by the Stefan-Boltzmann law of radiation: = aeAT4 where o 5.67x10-8 J/s - m2 K is the Stefan-Boltzmann constant, A is the surface area of the object, and T is its absolute temperature in kelvin. The symbol e stands for the emissivity of the object, which is a measure of how well it radiates An ideal jet-black (or black body) radiator has e 1,whereas a perfect reflector has...
1)(Hint: Cp=1.005 kJ/kg-K, Cv=0.718 kJ/kg-K, R=0.287 kJ/kg-K). An air-tight room contains 80 kg of air, and a 2-kW baseboard electric resistance heater in the room is turned on and kept on for 15 min. The temperature rise of air at the end of 15 min is 2)An example of when it is appropriate to model a substance as an ideal gas is when a. The pressure and temperature are close to the critcal point b. The pressure and temperature are...
265 A person is found dead at 5 p.m. in a room where temperature is 20°C. The (1 temperature of the body is measured to be 25°C when found, and the heat transfer coefficient is estimated to be 8 W/m2.K. Modelling the human body a 30 cm diameter, 1.70 m long cylinder.calculate actual time in hours) of death of the person. Take thermophysical properties of the body :k = 6.08 * W/m.K, p = 900 kg/m3,C = 4000 J/kg.K إجابت...