Chapter 5, Problem 5.10P

P.4 (Application on the First Law of Thermodynamics with heat transfer) A silicon chip measuring 5 mm on a side and 1 mm in thickness is embedded in a ceramic substrate. At steady state, the chip has an electrical power input of 0.225 w. The top surface of the chip is exposed to a coolant whose temperature is 20°C. The rate of energy transfer by heat between the chip and the coolant is given by 9= hA (T, - T), where T, and T, are the surface and coolant temperatures, respectively, A is the surface area, and If heat transfer between the chip and the substrate is negligible, determine the surface temperature of the chip, in °C.

1. In system, no mass can cross its boundary. However, it only allows energy transfer across its boundary o Control system o Closed system o Isolated system 2. Heat transferred to a system and work done by a system are always positive. o True o False 3. —— is a device that decreases the velocity of a fluid by increasing its pressure. o Nozzle o Diffuser o Compressor o Turbine 4. A heat engine may not reject any heat to a low-temperature reservoir and still can complete a cycle. o True o False 5. Heat is removed from the compartment of a refrigerator at a rate of 250 kJ/min. The refrigerator consumes 0.8 kW, determine the COP of the refrigerator. 6. It has been proved experimentally by joule that the internal energy is a function of o Temperature only o Pressure only o Volume only o All together 7. The combination of flow energy and internal energy gives - 8. A process during which there is no heat transfer o Adiabatic o Isentropic o Polytropic o Isothermal 9. Heat is transferred to a…

4.5 thermodynamics

1. A gas within a piston-cylinder assembly undergoes a thermodynamic cycle consisting of three processes: Process 1-2: Compression with PV = constant, from P₁ = 1 bar, V₁ = 2 m³ to V₂ = 0.2 m³, U₂ − U₁ = 100 kJ; 2 Process 2-3: Constant volume to P3 = P₁; Process 3-1: Constant-pressure and adiabatic process. Neglect the changes of kinetic and potential energy in all three processes. (a) Sketch the cycle on a P-V diagram; (b) Determine the net work (i.e., W12 + W23 + W31) of the cycle, in kJ; (c) Determine the heat transfer for process 2-3, in kJ. Hint: System's state variables remain unchanged after a cycle, i.e. (U₂ − U₁) + (U3 − U₂) + (U₁ − U3) = 0

3.5 thermodynamics

4. (2)

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A flywheel whose moment of inertia / = 200 lb-ft² is spinning at 210 RPM. For a flywheel, KE = Iw²/2, where w is the angular velocity, rad/s. Let g = 32.2 ft/s². Step 1 How high above the surface of the earth, in ft, would a 80 lb mass have to be raised to have its potential energy equal to the kinetic energy of the flywheel? h = i ft

A flywheel whose moment of inertia / = 200 lb-ft² is spinning at 220 RPM. For a flywheel, KE = Iw²/2, where w is the angular velocity, rad/s. Let g = 32.2 ft/s². Step 1 How high above the surface of the earth, in ft, would a 70 lb mass have to be raised to have its potential energy equal to the kinetic energy of the flywheel? h = 23.547 Hint Your answer is correct. Step 2 h = i How high above the surface of the earth, in ft, would a 110 lb mass have to be raised to have its potential energy equal to the kinetic energy of the flywheel? eTextbook and Media ft Save for Later Attempts: 2 of 4 used ft Attempts: 0 of 4 used Submit Answer