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The performance of a device is defined as the ratio of the desired output to the required input, and this definition can be extended to nontechnical fields.
A fine copper wire(0.07-cm diameter) is initially heated to 175C. The wire is suddenly exposed to an environment at 40C with a heat-transfer coefficient of 60W/(m^2*C).
Water vapor enters a compressor at 50 kPa and 150 C, and leaves at 400 kPa with the same specific entropy as at the inlet. What is the temperature of the water at the compressor exit.
Based on inernal energy considerations, what dislocation density in Cu is needed to make the crystalline form of Cu unstable with respect to the liquid form? What would be dislocation spacing be at
What is the approximate ductility (%El) of a brass alloy that has a yield strength of 275MPa? What is its Tensile strength?
A single crystal of aluminum is oriented for a tensile test such that its slip plane normal makes an angle of 30o with the tensile axis. Three possible slip directions make angles of 58.4o, 72o, and
Consider a single crystal cylindrical specimen of iron oriented such that a tensile load is applied along a [010] direction. The diameter of the specimen is 0.5 cm.
In a PEM fuel cell, there are catalyst particles dispersed in the catalyst layer (CL) to increase the electrochemically active area. You model this as jo=jo sigma, where sigma is the catalyst layer
Consider a large vessel divided into two chambers by a dividing nwall, such as that described in lecture on 23 Feb. The vessel and its contents are at 298 K and the dividing wall is 0.001 m thick ru
The yield stress of a tension specimen machined from a 0.5 m wide by 0.6 cm thick copper sheet is 145 MPa. The sheet is rolled further in the plane of the sheet with an applied tensile force of 0.22
The 50-mm radius pulley A of the clothes dryer rotates with an angular acceleration of alpha = 24*(theta)^(1/2) rad/s^2, where theta is in radians. Determine its angular acceleration when t = 2s, s
Determine the horsepower input for a motor necessary to lift a 200 kg box at a constant rate of 2 m/s. The overall efficiency of the system is 0.8.
A steam turbine produces 3000 hp with a mass flow rate of 22,000 pounds per hour. The steam enters at 1100 °F and 900 psi and exits at 2.5 psi.
What is the temperature at the exit of the valve in oC? what is the internal energy (kJ/kg) of the refrigerant at the exit of the valve?
An insulated,thin walled pipe of 100mm diameter is used to transport water to equipment that operates outdoors and uses the water as a coolant.
Assume the density of air is 1.16 kg/m3, and neglect the weight of the ropes and the cage. (b) Also, determine the maximum amount of load, in kg, the balloon can carry.
A single degree of freedom system has a concentrated mass weighing 38.6 lb, a spring constant of 22.5 lb/in and a damping coefficient of .6 lb-sec/in.
What is the thermal resistance associated with a wall that is 2.5m high by 6.5m wide ( having 10 studs, each 2.5m high)? assume surfaces parallel to the x-direstion are adiabatic.
Determine (a) the initial and final temperatures, (b) the mass of liquid water when the piston first starts moving, and (c) the work done during this process. Also, (d) show the process on a P-v dia
Cold water (c_p = 4.18 kJ/kg*C) leading to a shower enters a well-insulated, thin walled, double-pipe, counter-flow heat exchanger at 10 C at a rate of 0.95 kg/s and is heated to 70 C by hot water (
The energy generated within the house from people, lights, and appliances amounts to 4,500 kJ/h. For a COP of 2.5, determine the power input to the heat pump in kW.
If the plant uses 28.7 kg/s of coal as its fuel and coal has a nominal heating value of 32,000 kJ/kg, what is the overall efficiency of the plant (in percent)?
A bar of high strength aluminum alloy is 150 mm long and has a circular cross section of diameter 40mm. It is subjected to a tensile load of 250kN, which gives a stress well below the material's yie
Steam enters an adiabatic turbine at 3 MPa and 350 celsius and leaves the turbine at 75 kPa with a quality of 89%. IF you can neglect the potential energy effects, the inlet velocity is 100 m/sec an