Interview Mechanical

Mechanical Engineering Interview Questions Set-1

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

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

 

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

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

 

  1. What is gear ratio?

Ans = It is the ratio of the number of revolutions of the pinion gear to one revolution of the idler gear.

 

  1. Explain Otto cycle.

Ans. Otto cycle can be explained by a pressure volume relationship diagram. It shows the functioning cycle of a four stroke engine. The cycle starts with an intake stroke, closing the intake and moving to the compression stroke, starting of combustion, power stroke, heat exchange stroke where heat is rejected and the exhaust stroke. It was designed by Nicolas Otto, a German engineer.

 

  1. What kinds of pipes are used for steam lines?

Ans. Normally galvanized pipes are not used for steam. Mild steel with screwed or welded fittings are the norm. Pressure and temperature are very important factors to be considered in what type of materials to be used. Steam even at low pressures can be extremely dangerous.

 

  1. What is the alloy of tin and lead?

An. A tin and lead alloy is commonly called solder. Usually solder is a wire with a rosin core used for soldering. The rosin core acts as a flux.

 

  1. What is a uniformly distributed load?

Ans. A UDL or uniformly distributed load is a load, which is spread over a beam in such a way that each unit length is loaded to the same extent

 

  1. What is enthalpy?

Ans. Enthalpy is the heat content of a chemical system.

 

  1. Explain the second law of thermodynamics.

Ans. The entropy of the universe increases over time and moves towards a maximum value

 

  1. What is a Newtonian fluid?

Ans. 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.

 

  1. How does iron ore turn into steel?

Ans. 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.

 

  1. What does Green field project mean?

Ans. 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

 

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

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

 

  1. What is the role of nitrogen in welding?

Ans. 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.

 

  1. What is extrued aluminum?

Ans. 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.

 

  1. What is isometric drawing?

Ans. It is a 3-D drawing used by draftsmen, architects etc

 

  1. Which conducts heat faster steel copper or brass?

Ans. Copper conducts heat faster than steel or brass. Any material that is good for conducting heat is also good for electricity in most cases. Wood terrible for transferring heat thus is also insulator for electric.

 

  1. What kinds of pipes are used for steam lines?

Ans. Normally galvanized pipes are not used for steam. Mild steel with screwed or welded fittings are the norm. Pressure and temperature are very important factors to be considered in what type of materials to be used. Steam even at low pressures can be extremely dangerous.

 

  1. What is ferrite?

Ans. Magnetic iron rock

 

  1. What is the difference between shear center flexural center of twist and elastic center?

Ans. The shear center is the centroid of a cross-section. The flexural center is the center of twist, which is the point on a beam that you can add a load without torsion. The elastic center is located at the center of gravity. If the object is homogeneous and symmetrical in both directions of the cross-section then they are all equivalent.

 

  1. What is the difference between projectile motion and a rocket motion?

Ans. A projectile has no motor/rocket on it, so all of its momentum is given to it as it is launched. An example of a projectile would be pen that you throw across a room.

A rocket or missile does have a motor/rocket on it so it can accelerate itself while moving and so resist other forces such as gravity.

 

  1. What does F.O.F. stand for in piping design?

Ans. FOF stands for Face of Flange. A flange has either of the two types of faces:

  1. a) Raised face
  2. b) Flat face

The F.O.F is used to know the accurate dimension of the flange in order to avoid the minute errors in measurement in case of vertical or horizontal pipelines.

 

  1. What is annealing?

Ans. It is a process of heating a material above the re-crystallization temperature and cooling after a specific time interval. This increases the hardness and strength if the material.

 

  1. What are the differences between pneumatics and hydraulics?

Ans. a) Working fluid: Pneumatics use air, Hydraulics use Oil

  1. b) Power: Pneumatic power less than hydraulic power
  2. c) Size: P components are smaller than H components
  3. d) Leakage: Leaks in hydraulics cause fluid to be sticking around the components. In pneumatics, air is leaked into the atmosphere.
  4. e) Pneumatics obtain power from an air compressor while hydraulics require a pump
  5. f) Air is compressible, hydraulic oil is not

 

  1. Which conducts heat faster steel copper or brass?

Ans. Copper conducts heat faster than steel or brass. Any material that is good for conducting heat is also good for electricity in most cases. Wood terrible for transferring heat thus is also insulator for electric.

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Mechanical Engineering Interview Questions Set-2

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