Mechanical Engineering Interview Questions and Answers
Question - 31 : - What Does A Rolling Offset Look Like?
Answer - 31 : - Rolling offsets are used in the piping and sheet metal (ductwork) trades, a rolling offset changes the elevation and locaton of the piping or duct usually by using two fittings to offset around obstacles. Rolling offsets are used mostly when you are limited to the size of the fittings in order to change your elevation and location.
Question - 32 : - What Kind Of Paper Airplane Flies The Farthest?
Answer - 32 : - Thickest paper has the greatest mass and therefore potential energy. Potential energy equals kinetic energy (speed). Speed equals lift. Lift equals a greater flight distance. Thicker planes fly farther.
Question - 33 : - How Does An Equal-arm Balance Work?
Answer - 33 : -
Two pans of equal balances are placed at the end of the beam, one at each end. A long pointer attached at right angles to the beam at the point of support. Zero on a scale indicates the beam is at rest.
Question - 34 : - What Is Wet Corrosion And Galvanic Corrosion?
Answer - 34 : -
Galvanic corrosion is an electrochemical process in which one metal corrodes preferentially when in electrical contact with a different type of metal and both metals are immersed in an electrolyte.
When two or more different sorts of metal come into contact in the presence of an electrolyte, a galvanic couple is set up as different metals have different electrode potentials. The electrolyte provides a means for ion migration whereby metallic ions can move from the anode to the cathode. This leads to the anodic metal corroding more quickly than it otherwise would; the corrosion of the cathodic metal is retarded even to the point of stopping. The presence of electrolyte and a conducting path between the metals may cause corrosion where otherwise neither metal alone would have corroded.
Wet Corrosion: The main feature of corrosion of a divalent metal M in an aqueous solution containing oxygen is because of the corrosion process consists of an anodic and a cathodic reaction. In the anodic reaction (oxidation), the metal is dissolved and transferred to the solution as ions M2+. The cathodic reaction in the example is reduction of oxygen. It is seen that the process makes an electrical circuit without any accumulation of charges.
The electrons released by the anodic reaction are conducted through the metal to the cathodic area where they are consumed in the cathodic reaction. A necessary condition for such a corrosion process is that the environment is a conducting liquid (an electrolyte) that is in contact with the metal. The electrical circuit is closed by ion conduction through the electrolyte. In accordance with the conditions, this dissolution process is called wet corrosion, and the mechanism is typically electrochemical.
Question - 35 : - How Do Concrete Pumps Work?
Answer - 35 : - liquid (fluid) concrete has a big viscosity, how the pump overcomes this big viscosity. every couple seconds maybe 4-5 seconds the machine emits a loud thump. sound come from pnomatic part of the machine.
Question - 36 : - What Is Representative Elementary Volume?
Answer - 36 : - Smallest volume over which measurements can be made that will yield a representative of the whole.
Question - 37 : - How Can You Convert Air Mass To Air Volume?
Answer - 37 : -
Mass = density * volume.
Air density is p/RT, where R is the gas constant for air (287 J/kg-K), T is the absolute temperature, and p is the pressure, equal to 101325 Pa at sea level.
At sea level and room temperature, the density of air is rho 101325 N/m2/ (287 N-m/ (kg-K)*293 K or about a) 2 kg/mc)
Question - 38 : - What Are Different Types Of Gate Valves?
Answer - 38 : -
There are a few different designs:
Parallel disk gate valves use two disks with a spring in between them, sliding into the seats. At low pressure, the spring forces the disks outward against the seats, sealing off the valve. At high pressure, all the sealing is accomplished by the downstream disk.
Wedge gate valves use a tapered disk that slides into two seats set at a slight, converging angle. The wedging action provides the sealing force between the disk and the seat.
Single disk gate valves are used where the flow is always one-way (like sluices on dams). There is some flexibility in the attachment of the disk to the stem, so the differential pressure on the disk pushes it against the seat, sealing it off.
Question - 39 : - What Is The Density Of Plastic?
Answer - 39 : -
Plastics are the general term for a wide range of synthetic or semisynthetic polymerization products. There are many different plastics; all have their own density!
Most common plastics, however, have a density between .035 and .045 lb/cu in.
Question - 40 : - What Is An Ortographic Drawing?
Answer - 40 : -
Orthographic projections are views of a 3D object, showing 3 faces of it. The 3 drawings are aligned so that if the page were folded, it would create part of the shape. It is also called multiview projections.
The 3 faces of an object consist of its plan view, front view and side view. There are 2 types of orthographic projection, which are 1st angle projection and 3rd angle projection.