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Questions in engineering

[Done] Select the best answer for the question. 19. The wires connecting three-way switches are called A. switch feeds. B. travelers. C. grounds. D. neutrals.

[Done] Place the steps of threading a pipe in order: Apply oil and slide the die over the pipe, so the ratchet handle is pointing right. Turn the ratchet handle, lubricating as needed. Insert the die into the ratchet handle. Remove the die head. Cut the pipe to the necessary length.

[Done] Use the Laplace transform to solve the given initial-value problem. [tex]y^{\prime \prime}+y=\sqrt{2} \sin (\sqrt{2} t), y(0)=8, y^{\prime}(0)=0[/tex] [tex]y(t)=[/tex]

[Done] Which rope cannot be reused for any reason? A. Throwline B. Escape ropes C. Broken rescue ropes D. Life safety ropes

[Done] Select the best answer for the question. Why are systems with fixed-restriction metering devices critical to charge? A. The expansion device can't adjust to changing conditions. B. They can be charged only one time. C. The large liquid receivers hold so much refrigerant. D. You must weigh both the system and the refrigerant.

[Done] What items are normally found in a NEMA Standard? Select all that apply, then select Submit. Marking Terms Rating Warranty

[Done] Consider the following inverse forms: [tex]$L ^{-1}\left{\frac{s-a}{(s-a)^2+b^2}\right}=e^{a t} \cos (b t)$[/tex] and [tex]$L ^{-1}\left{\frac{b}{(s-a)^2+b^2}\right}=e^{a t} \sin (b t)$[/tex] Use the Laplace transform and these inverses to solve the given initial-value problem. [tex]$y^{\prime}+y=e^{-3 t} \cos (2 t), \quad y(0)=0$[/tex] [tex]$y(t)= \square$[/tex]

[Done] Choose all options that apply. In a refrigeration system, moisture causes which of the following? a) Corrosion b) Valve failure c) Freeze-up of the expansion valve d) Motor insulation damage e) Solid contaminants

[Done] True or False: As a standards organization, NEMA produces publications for installation groups only.

[Done] How does a fluorescent dye leak detector work? A. It dyes the refrigerant so that escaping gas leaves a visible cloud. B. It's applied evenly to the outside of an area suspected of a leak. C. It dyes the refrigerant oil so that escaping oil leaves traces of dye. D. It's used in conjunction with ultrasonic detectors to improve the resolution of the mechanical ultrasou