Question Set 123

31. What causes white smoke in two stroke locomotive engines?

That is the engine running too lean (lack of fuel). This condition will lead to overheating and failure of the engine.

32. What is the role of nitrogen in welding?

Nitrogen is used to prevent porosity in the welding member by preventing oxygen and air from entering the molten metal during the welding process. Other gases are also used for this purpose such as Argon, Helium, Carbon Dioxide, and the gases given off when the flux burns away during SMAW (stick) welding.

33. What does Green field project mean?
Green field projects are those projects, which do not create any environmental nuisance (pollution), follows environmental management system and EIA (environment impact assessment). These projects are usually of big magnitude.

34. Is it the stress that, produces strain or strain produces stress?

A Force applied to an object will cause a displacement. Strain is effectively a measure of this displacement (change in length divided by original length).
Stress is the Force applied divided by the area it is applied. (E.g. pounds per square inch)
Therefore, to answer the question, the applied force produces both “Stress and Strain”. “Stress and Strain” are linked together by various material properties such as Poisson's ratio and Young's Modulus.

35. How does iron ore turn into steel?

To make Steel, Iron Ore is refined into iron and all the carbon is burned away using very high heat (Bessemer). A percentage of Carbon (and other trace elements) are added back to make steel. 36. What is knurling?
Knurling is a machining process normally carried our on a centre lathe. The act of Knurling creates a raised criss-cross pattern on a smooth round bar that could be used as a handle or something that requires extra grip.

37. What is the mechanical advantage of a double pulley?

It only takes half the effort to move an object but twice the distance.

38. What is extrued aluminum?

Extrusion is the process where a metal or a metal bar is pulled through a mandrel to elongate it and/or give it a final shape.
Extruded Aluminum is a common form of making small aluminum wire, bars or beams and many varieties of small non-structural, decorative pieces.

39. What is a Newtonian fluid?

A Newtonian fluid possesses a linear stress strain relationship curve and it passes through the origin. The fluid properties of a Newtonian fluid do not change when any force acts upon it.

40. What are the points in the stress strain curve for steel?

Proportional limit, elastic limit or yield point, ultimate stress and stress at failure.