Engineering

Conductivity is the reciprocal of what?
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Which materials were used to make the fuselages of the first airplane?A. wood and fabriccheB. metal and woodfabric and plasticD. wood and ceramic
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3. An underground copper pipe is used to transport oil under a factory. It is very important that this pipe does not oxidize, so engineers use impressed current cathodic protection. a. Would zinc be an appropriate metal to use for cathodic protection? Why or why not? (4 points) b. Engineers attach a sacrificial anode to the copper pipe. To use impressed current cathodic protection, they must attach a battery between the cathode and anode. Which material should the positive side of the battery be attached to? Explain how you know. (4 points)
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Engineers mainly concentrate on ____.a. creating new ideas (such as designing hydrogen-powered automobiles)b. modifying existing ideas (such as designing a fast computer)c. creating ideas and then implementing themd. both a and b
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Based on the hardness values determined in Part 1, what is the tensile strength (in MPa) for each of the alloys? (a) 0.25 wt%C with spheroidite, (b) 0.25 wt%C with coarse pearlite, (c) 0.60 wt%C with fine pearlite, and (d) 0.60 wt%C with coarse pearlite. The tolerance to all answers is +/-10 %.
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Tech A says that a transistor has a single PN junction. Tech B says that a transistor is a semiconductor device used as a switch and to amplify currents. Who is correct? Group of answer choices
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An 8-m long, uninsulated square duct of cross section 0.2m x 0.2m and relative roughness 10^-3 passes through the attic space of a house.. Hot air (80C) enters an 8 m long un-insulated square duct (cross section 0.2 m x 0.2 m) that passes through the attic of a house at a rate of 0.15 m^3 /s. The duct is isothermal at a temperature of 60C. Determine the rate of heat loss from the duct to the attic space and the pressure difference between the inlet and outlet sections of the duct.
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Assume you have created a class named MyClass and that is contains a private field namedmyField and a nonstatic public method named myMethod(). Which of the following istrue?a. myMethod() has access to and can use myFieldb. myMethod() does not have access to and cannot use myFeild.c. myMethod() can use myField but cannot pass it to other methods.d. myMethod() can use myField only in myField is passed to myMethod() as aparameter.
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A fixed mass of saturated water vapor at 400 kpa is isothermally cooled until it is a saturated liquid. Calculate the amount of heat rejected during this process in kJ/kg.
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Define centrifugal pump. Give the construction and working of centrifugal pump.
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Engineers are looking for a new material to build the body of an airplane. They agree that the material must be lightweight, but also strong and long-lasting. Above all, the material must maximize the safety of the passengers. Several engineers have developed some initial plans. Which stage of technological design is described in this passage
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how to build a laser pointer?
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In a series motor, the field electromagnet consists of A) a winding connected in parallel with the armature. B) a winding connected in parallel with the armature and a second winding connected in series with the armature. C) a winding connected in series with the armature. D) a winding connected in series with a separate dc power source.
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Assume a regulator has a percent load regulation of 0.5%. What is the output voltage at full-load if the unloaded output is 12.0 V
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Explain orthographicand multi-viewprojection
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A single-threaded power screw is 35 mm in diameter with a pitch of 5 mm. A vertical load on the screw reaches a maximum of 5 kN. The coefficients of friction are 006 for the collar and 009 for the threads, while the frictional diameter of the collar is 45 mm. Find the overall efficiency and the torque to raise and lower the load for
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Water discharging into a 10-m-wide rectangular horizontal channel from a sluice gate is observed to have undergone a hydraulic jump. The flow depth and velocity before the jump are 0.8m and 7m/s, respectively. Determine (a) the flow depth and the Froude number after the jump (b) the head loss (c) the dissipation ratio.
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If you think a hazard is serious, what is the best way to ensure that OSHA willconduct a site inspection?Help
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In a particular application involving airflow over a heated surface, the boundary layer temperature distribution may be approximated as
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All hermetic compressors require a crankshaft seal.TrueFalse
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A student lab group is brainstorming the design of an experiment that uses an ammeter (measures current) and different resistors to determine the effect of the resistance of a resistor upon the current in a simple circuit. Which Post-it note describes the most effective design?Put a 10.0-ohm resistor in the circuit. Measure the current in the circuit. Replace the 10.0-ohm resistor with a 20.0-ohm resistor. Measure the new current. Continue replacing the resistor with a different resistor of known resistance. Measure the current for each resistor. Record all data. Put a 10.0-ohm resistor in the circuit. Measure the current in the circuit. Move the ammeter to a different location in the circuit. Measure the current at this new location. Continue moving the ammeter to different locations within the circuit but be careful to keep the resistor in a fixed location. Measure and record all current values. Obtain a variety of batteries and build several circuits. Make sure that each circuit has at least one resistor and make sure that the resistance values are different in the different circuits. Place various ammeters in each circuit. Measure the number of batteries and the current for each of the circuits. Record the resistance values used in each of these circuits. Put a 10.0-ohm resistor in a circuit with a single D-cell. Measure the current in the circuit. Add a second D-cell and measure the current with two D-cells. Repeat trials for three, four, and five D-cells, being careful to get accurate current measurements for a fixed amount of resistance in each trial.
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B1) 20 pts. The thickness of each of the two sheets to be resistance spot welded is 3.5 mm. It is desired to form a weld nugget that is 5.5 mm in diameter and 5.0 mm thick after 0.3 sec welding time. The unit melting energy for a certain sheet metal is 9.5 J/mm3 . The electrical resistance between the surfaces is 140 micro ohms, and only one third of the electrical energy generated will be used to form the weld nugget (the rest being dissipated), determine the minimum current level required.
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Air at 1 atm, 15C, and 60 percent relative humidity is first heated to 20 C in a heating section and then humidified by introducing water vapor. The air leaves the humidifying section at 25C and 65 percent relative humidity. Determine:a. the amount of steam added to the air. b. the amount of heal transfer to the air in the heating section.
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Water at 20oC, with a free-stream velocity of 1.5 m/s, flows over a circular pipe with diameter of 2.0 cm and surface temperature of 80oC. Calculate the average heat transfer coefficient and the heat transfer rate per meter length of pipe.\
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