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Questions in engineering

[Done] An HVACR service technician has been called in to inspect a system with a line leak. She sees that the refrigerant line has been in direct contact with a concrete block wall. How might this have contributed to a leak? Vibration Lack of stability Corrosion Pressure on the joints

[Done] The issue of overheating due to excessive compression ratios is prevalent in what type of refrigeration system? A. Remote piped systems B. Low-temperature systems C. High-temperature systems D. Medium-temperature systems

[Done] A mat foundation has dimensions of 40 m x 20 m. The live load and dead load on the mat are 250 MN. The mat is placed over a layer of soft clay that has a unit weight of 19 kN/m³. Find Dr for a fully compensated foundation.

[Done] Match the parts of an electronically controlled expansion valve to their functions. 1. Remotely controlled valve 2. Thermistor 3. Transformer * Placed in the refrigerant stream near the evaporator outlet to respond quickly to temperature changes * Transmits a voltage change to an electronic controller * Adjusts opening in metering devices

[Done] What does mutual inductance depend on? A. Resistance between the coils B. Coupling coefficient and inductances C. Voltage across the coils D. Capacitance of the system

[Done] A square steel bar is 50 mm on a side and 250 mm long. It is loaded by an axial tensile force of 200 kN. If E = 200 GPa and v = 0.3, determine the change of volume per unit volume. Options: 1) 0.000823 2) 0.0234 3) 0.0002 4) 0.00016

[Done] Which of the following statements is true regarding modes of operation in vehicles featuring eAWD? A. They have either a transfer case or power transfer unit (PTU). B. They have independent electric drive transmissions. C. The transmission may feature one or two drive motors. D. Both B and C.

[Done] What is the reason for slowing down just before completing a hacksaw cut? A. to keep from dulling the blade B. to prevent the blade from breaking C. to prevent the surface being sawed from slipping D. to prevent injury to hands

[Done] Which larger capacity compressor uses two meshing rotors to compress refrigerant vapor? A. Scroll B. Reciprocating C. Rotary-vane D. Screw

[Done] 11. Tellegen's theorem is applicable to: a) Non-linear, non-reciprocal networks only b) Linear, time-invariant networks only c) Any lumped network satisfying Kirchhoff's laws d) Only DC circuits with independent sources